I'm so sorry for what you're going through. I can relate as I have a 32+year marriage that seems to be headed in the same direction...and I still love him dearly, but he moved out almost a year ago. Neither one of us is willing to make the first step towards legal separation...something keeps us both hanging on...and it hurts.
It sounds to me like your husband is going through the same thing mine did...a mid-life crisis that messes with their minds in ways that are so hard to understand...even for them, but especially for us.
You also have time to possibly turn things around if that's what you truly want while you are together and not living apart. There is couples counseling and mediation lawyers who focus on keeping couples together and not just on divorce.
Forgiveness for infidelity is rough, but do-able if you truly love someone. I wish you the best!

I am very sorry for your situation. The same thing happened to this author, but had they not taken the step to file, things could have gone on much longer and gotten much worse:

https://www.amazon.com/dp/1693393220

If your spouse is already moving on with their lives, and you keep hoping for a miracle, you may come to find out that, like the author of the book, they were being bled dry financially. Please be sure to think through the impacts that could come to you while waiting for a miracle.

Alice: If you get back together with him, which I hope you do not, have him get tested for STDs since he has been with others. Protect yourself financially and physically. I am glad you are seeing a Lawyer. This is not a good marriage and I think you are better off out of it. Best wishes.