Hello Tom,
I applaud your honesty in your post; it took courage for you to share openly.
It's a hard position you are in right now and I can only imagine how painful it must be for you.

Jmo, of course, but perhaps giving your wife some space right now may be a good idea for both of you. From what I understood, you are making every effort to change some things that have hurt your marriage. It shows your willingness to try and I think it's commendable.

It's hard for me to understand why your wife would tell you she sent this man her undies...payback of some kind in order to hurt or anger you comes to mind.

There are so many past issues that need to be addressed with a qualified therapist, and I hope you can find one that both of you will be comfortable with...
It may be hard for your wife to share since she has "stuffed" her feelings out of fear for so long, but hopefully she will give it a try.
Patience will have to be a two way street, and honored while the other works through their feelings.
Your daughters may also benefit from some type of counseling, it's as confusing at their ages as it would be if they were younger.
It's so important not to put them in the middle or make them choose between you and your wife.

A miracle? Perhaps.
If it does happen it will be from you and your wife going to counseling, being fair and honest with each other, and also listening--really listening--to what the other is sharing...

Best wishes,

Catherine