Take a deep breath. You don't have to decide anything today. This is going to be a process regardless of the outcome. There are so many what ifs there is no point in constantly ruminating about them.
My guess is she doesn't see this as cheating anymore. She's told you she's done, doesn't love you and has "moved on".
Even when the honeymoon phase is over it doesn't mean she's not going to want him, and even if she doesn't, it doesn't mean she's coming back to you.
Don't worry about her and what she is doing. You can not control that in any way shape or form. Control you, control what you can, and start getting a life like a mad man. Become the best you, you can be. Be a man that woman will respect and be attracted too.
Me: 40 EX:37 Together 17 years Married 16 years 5 kids, 20,18,15,14,11