Been there done that except that nonsense went on for way longer. So although this may come across as curt, I get it....
1) if you are afraid that you are a ticking time bomb you probably are. One of our posters once wrote here, and I still remember, these things never end well
2) that would be correct, you cannot be friends.
3) Even if he wants to see you, it's what you want.

Which brings me to my thoughts:
1) what is you want? Do you really want to end this (and it's ok if the answer is no or not really, there's help for that also..... For months last year I really didn't want to end it, I ended it because I felt I had to)
of it's not really want you want, it's not going to work. It really really has to be an active decision:"I will not cheat on my husband". Period.
2) do whatever works: a) make lists of all the qualities he has that aren't that great. Make lists to compare him to your H. Take it one minute or one hour or one day at a time. It's definitely not easy and in the process you'll do more soul searching that eventually you've just had enough
3) get IC if you need it
4) when you want to text, put down the phone..... Play mind games with yourself 'I'll revisit this urge in 6 hours", go for a walk, make a to do list, go for a drive, come here, read, write journals, make friends.

In summary it really all came down to a decision for me. Do I want an A? Or do I want my husband and a marriage that is open, connected, and just ours. And please know it took me YEARS to be as comfortable with saying that as I am now and please know I still have MANY difficult days and it is not easy at all. In fairness one of the hardest things I've ever experienced, but I have regretted it..... Although I've only been 'clean' as I say for less than 6 months.

Good luck! We are here for you!!!

"Then for 8 months we didn't see each other, but still texted and emailed."
Here is I think that where things went really wrong---it is bad enough to have had the affair, but continuing contact continued the destruction and ultimately got you right back where you don't want to be. You cannot be "just friends" with this person. You know that.

Your situation is different from many others because the actual PA has seemed to just go on from April-August each year. Why is that? Why the break in the time, and who initiated that break?

Do you want your marriage???? Do you love your husband? If so, what you have to do is make the decision to THINK. You need to make the decision to be intelligent about this---from the post, it does not sound like you necessarily want the affair, but you are weak enough to allow it to happen, you are letting your feelings and neurotransmitters such as Dopamine run your life. Allow (and require) your mind to run your life, not your feelings. Allowing one's feelings to run the show is never a good idea.

The only way to heal and get out of the tangled web is by going no contact. That is also the best thing for your AP too, so he can also move on with his life. Both of you are going down a dead-end street with things as they are.

It sounds like, because of your weakness, you need to block him from social media, text, phone, etc. to make this work.
I wish you the best.

It's so much easier to say then to do, that's for sure......
But the fact you have that 6th sense that feeling that 'something isn't quite right here'..... It's a good beginning.

Talk to yourself like you would a best friend that you love and has your best interest in mind. It's hard to let go, but that's the first step. Take a breath, step outside, get some fresh air and remind yourself of who you are and who you want to be.

There is one interesting fact that Sarah brought up about the timing thing...... ALL of my A's started in the Fall (which may be why I'm feeling so much anxiety now) and for me, I can directly relate the timing to an extremely traumatic event the began in the Fall and cumulated through the winter that I did suffer PTSD from. It wasn't an excuse it was more like an interesting phenomenon.

Thanks for the replies. I really do appreciate it and it's good to get advice from people who have been exactly where I am right now. My AP is the one that broke things off last August. He said he started to feel guilty and said that we should both just work on our marriages. But… We continued to stay in contact with each other. I think that is very difficult for both of us to imagine never talking to the other one ever again. And I wish that I could go back in time and undo the affair and just remain friends with him. I know that that is not possible though. The thought of completely cutting contact with him And never talking to him ever again though, makes me panicky. There's this piece of me that feels like I could try to just be friends with him and just have occasional contact. But, at the same time, anytime I do get in contact with him, I know that things always turn flirty and we end up talking about seeing each other. We both admittedly have feelings for each other still. I just really feel very lost a lot of the time.
But then, there's the flipside. I don't want to lose my husband and children. And I know that if I continue the way I am that eventually it's going to blow up in my face.

you wrote--"And never talking to him ever again though, makes me panicky. There's this piece of me that feels like I could try to just be friends with him and just have occasional contact. "

You know deep down that is not true. In order for him to be a true friend, if you want your marriage, the AP needs to be a TRUE friend of your marriage. Not just a "friend" to you. I do not think that the AP can be that, as the AP is obviously not supportive of your marriage (or his)--quite the opposite. Friends do not create chaos and heartache in their friends' marriages. You might need to rethink your definition of a friend.

You talk a lot about feelings in your post. You need to clear your head of these feelings and the only way to do it is by going no contact.

If you want your marriage and don't want to hurt or lose your H and children, you must walk away. The sooner the better. Don't you think that your H and children are more important to you than a man who is also a cheater??? Think. Stop weaving the tangled web.

Also it has been said, and I think that this carries a lot of validity--

"If they will do it with you, they will do it to you."

What that means is that even if you were to end up married to the AP down the road, chances are that he would cheat. The best predictor of future behavior is past behavior. More heartache. Do you really want to sign up for more heartache?

I don't mean to sound harsh, in case you are thinking this is a bit harsh. I really am trying to help.

Sarah… I know you weren't trying to be harsh. And I think that you told me a lot of things that I really need needed to hear and need to think about. In a way, it kind of makes me feel bad because just as you said that he's not being a true friend because he's not respecting my marriage and his own… That means that obviously I'm not being a true friend to him either because I'm not respecting his marriage, mine or his wife.
I think it's much easier for men to be able to compartmentalize things. And to him… At this point… Although he admits that he still loves me, it's become more of a physical thing for him. He admitted to me that he felt more guilty about the emotional parts, then the physical aspect. I think he felt that the emotional aspect was more betraying to his wife and the physical part. Even though I think we can all agree that as a wife, I would feel betrayed by either.
A lot of tough things to think about, for sure. But I know I need to work on that.

Maybe since he has experienced guilt also, both of you could agree that emotionally betraying your spouses has to stop, and that no contact is the only way to insure that, as hard as it is to do that.

Maybe you two could also agree that you have not been friends to each other, each others marriages, your spouses or the AP spouses.

Maybe then you could agree that going no contact immediately is what needs to happen.

And both of you could agree to sticking to your guns on the no contact thing.

And if he does not agree, maybe you will have to do these things on your own, and block him.

The sad thing is is that I think that he would probably readily agreed we need to go no contact. He had said that once or twice before that eventually that's what's going to have to happen. Part of my hesitation to go no contact is the fact that I think it would be easier for him. But it wouldn't at all be easy for me. And that hurts me more.

It might be easier for him to go no contact, maybe it won't. If it is easier for him, perhaps he needs to block you from his social media and phone, as well as you blocking him. That way there will be no wondering who it is when the phone rings if you two can't contact each other easily.

Who this is harder on is not the issue---it is about doing the right thing and ending the madness before even more damage is done. It sounds like you both know what needs to happen.

The other thing is that it will take time for you to heal. It is not going to be easy. But the decision is now how long do you now add more pain by prolonging the time of beginning the healing process?