I had 20 years invested. I didn't find out he was cheating until after he left.
Very long story short...
I wouldn't trade a step of the pain and confusion of the early aftermath. I learned so much about myself and how I had completely lost myself in that relationship.
I put in some serious me time and on the other side, found a man who appreciates me as much as I do him.
If I had to go through that mess to get here---I'd do it again.
Learn how to be good to you and you will attract people who will do the same.
Good luck and stay strong.