I think your idea of letting it go, and just dealing with your issues is the best idea. Things like this always get "found out" anyway by the 'unknowing' partner, without you having to tell her. So it's best to stay out of it and let nature take it's course. It's going to get ugly enough without you getting into it.

At least this way, you may have a better chance of getting your ex back without having gotten into the mess. I hope it happens that you get her back if that's what you REALLY want. God bless and please take care. Hugs, Lee