Okay, I've been there. It helped me a LOT to learn that the human brain cannot do two things at once, at least not well. This is why when we humans try to drive and text, we often end up having some pretty bad car accidents.

Use this knowledge to your benefit. If you are focusing on an arts and crafts project, or learning a new language, or learning a new skill, you will not be able to focus on That Guy.

Give it a try.

I have another theory, try exhausting the thought of him. Talk about him a LOT and your feelings too! Talk until it is out of your system. It's like watching a movie, eventually if you watch it enough times, you're bound to tire of it. The issues of infidelity my ex had in the past...I hardly talk about that anymore because I just talked about it so much, I acknowledged the feelings that I had and the affair(s). At this point, that's old news to me. :) others may totally diagree with me, but again this is my theory.

Journal - go for therapy - get all of those feeling out. Time is your friend. You have to go through it to get through it. You will be OK - you can do anything and everything that he did. You are strong, you can do it. (Hugs)

good point.......keep busy.......well, keep your brain busy......! :)

Thank you all for the support! All were great ideas :) I agree if I talk about it a lot I will eventually get sick of it. But I do need to focus on other things too. I know I have plenty of time, I just feel like I will never meet someone else and my whole future is gone. I know this is irrational thinking.

I'm going through the same thing right now...and its not that easy. I need to end a relationship that should have never started. There are days when I obsess about him and certain situations. Besides trying to keep busy, I think of things that piss me off about him. Those things are helping me to bring this to an end.

TIME. I don't have much more than that, except, somehow, over time, he will slowly be filtered out of your life. When you're feeling like being sad, or down, (which we need sometimes) try to do something, even if you know you're only doing it for the sake of doing it. Get yourself out of the house, meet new people, try things you haven't done before.
Somehow, as time progresses, and you start becoming whole, he will lessen in your life. My EX is still around because of custody, but I no longer wait for texts, think about him constantly, etc. He is very much his own person,and I am mine.

At least you didn't waste 20 years. It's going to hurt, there is no way around it. Time is all you need, and eventually meet someone who fits you better.

I try to stay busy it makes me forget about somebody if I am hurting.