You've made some mistakes in the past, but you can recover from them, survive, and thrive - with or without your WS
I suspect you triggered many readers of your story. The story certainly triggered me, and my W had only a 4.5 month A. My heart goes out to you. I know you're in pain. I wish I could take it away, but I can't. You can, though, but you probably will need help.
First, most of us make mistakes. Many of us make the same mistakes you have made - allowing WS to make that phone call, not demanding answers, etc., etc., etc.
Hearing that you're not your W's love of her life is devastating. I didn't hear that; seven so, I had to do a lot of internal work to comprehend that my W's A was not because of any failure in me. Your W's A was not because of some failure in you. Your W cheated because of some failure(s) in her.
Remember: she met the love of her life and did nothing about it but cheat. She probably realized down deep that she was/is(?) lying to herself; otherwise, she would have left. This guy was an escape from dealing with her problems at work and at home. An escape from life, an escape from herself. She is no prize. I wish, for her sake, that she realized her problem was herself and that she did something productive about it, like find a good guide/IC/therapist.
You now have a problem, too, also with yourself. What do you need to do to (re)build your self-esteem enough to address your M issues? What do you need to do to process the pain of being betrayed out of your body? How do you make good decisions for your future?
I urge you to pick one of 2 paths. First, you can confront your W, tell her you recorded her phone call, and tell her you want either true R or (true) D. If she gets angry that you recorded her, I'd have a hard time NOT taking that as a sign that she's a lousy candidate for R. OTOH, if she quickly comes around to the position of being glad you recorded the call, starts working with a good therapist, and works with you to decide what you'll both do to R, she might be a good candidate for R. (hint: answering all questions is a requirement.)
My reco is not to confront unless you have decided that you will D if she doesn't step up.
If you're not ready to confront/D, my reco is to seek IC for you as a way of realizing you're stronger than you think and to find and enhance your strengths.
Do you really want to be with a woman who cheated on you for the remaining decades of your life? And wouldn't it be better to live alone than to live with someone you don't have any reason to trust? Frankly, at your age, there are a lot of good women out there who will want to be with you. You're only as stuck as you think.
Brother, I know you feel lost. You've lived through 17.5 years of hell with your W. But your post means you're ready to stop doing that. The hitch is that you won't get out of hell without taking action on your own behalf.