Welcome to the group. The fact that he's had issues with ED for some time does suggest he is probably not having an affair but simply does as many. ...just shuts down and goes through the motions.

Also the fact he hinted it was because of your weight rather than facing it may be his issues responsible is so typical.. Many men do develop issues with low testosterone that can be reversed if they simply check into it....

Good for you with shedding some pounds. That is easier said than done. Do not allow him to put the blame on you
Instead feel good about yourself and know you are still smart, attractive sexy and desirable regardless of what he thinks

I am sorry you are going through this, my wife is a heavy lady but I still sexualy desire her (we also have been 18 months since the last time we had sex) so I don't believe it's your weight and more in his mind.
I can't comment on Ed as I have never suffered from it but have had issues at time of stress. Have him go check his T levels that can be a big issue. I hope it all works out for you

My wife has given up on sex. She masterbates a bit but nothing for me. Most of life is good. I think it’s part she has no need for sex. It hooked me to get married and we have kids. After that the usefulness of initiation was lost on her. When you want it and the other person doesn’t it makes you crazy and I’ve thought she was cheating but it was me looking for an easy explanation. She has no desire for me. Makes me wonder what she thinks about when masterbating, I doubt it’s me cause she could have that anytime. She thinks it’s just age and premenopausal issues. But I get no real communication from her about sex it’s just ignoring the issue. I’ve stopped trying this time. Make her wonder why I stopped asking. She either will love it or question me. It’s been 4 mo and it’s hard for me to just see what happens. She thinks all women are like this. This site showed me that’s not the case. We’re all not crazy. Good for you on taking care of yourself. That should be your first priority in my mind. That way if you work on you. He’ll either work on himself or you’ll be stronger if you need to leave. I’m at the point where I don’t even think it’s cheating if I were to get my needs elsewhere because I’ve tried to address this for a decade and nothing from her. She either resents me too much, has no passion left or doesn’t care. How do you fix that? I keep coming back to the idea I need to get passion elsewhere. What is marriage or live without passion, to me it’s just roommates and coparents

Hand in there. Seek to understand what you can live with, confront the issue and do what best for you.

I’m so sorry you are experiencing this. I’m a 57 year old female and I can tell you not all women have low sexual desire. Though I’m married to a woman who has no sexual desires and nothing for me and it’s broken me. I truly understand how you feel as I need my needs to be desired met and if not by her I will have to grow the courage to leave. There is no fixing this. It’s not living when you desire sex and your partner through their actions tell you your needs are not important.

2 years for me as well. Wife says she is Asexual. Nothing fare about being neglected!