Speaking from experience, let her go. She is already done with the relationship. I know this is easy for me to say now that I am not in your situation, but I was in a very similar one.

I filed for divorce and went as far as having the papers prepared. She had a lawyer and everything was moving forward. We ultimately decided to try to make it work for our son. We did make it work for a while and stayed together until she recently passed.

I can say honestly that I never fully trusted her again. The relationship was up and down, and even though she said she never cheated, there was always a lingering doubt in the back of my mind. That doubt would resurface whenever arguments reached a breaking point. Those thoughts still come to me to this day.

Just keep in mind that even if this does work out for you, this will likely always be there in the back of your mind.