You said this all the way back on 1 May last year, OP. Do you remember?
If he wants to be with her, like you say, why does he continue to live with me under one roof? He isn't forced to stay.
Lots of people told you why. Yet here you are, many months later, still asking exactly the same questions and ignoring all the answers and advice you get. You seem to think that you've 'won' over the OW, that you've performed the Pick-Me Dance better than she has, that your H has chosen you over her, and that this is a triumph for you and proves that your H loves you and cares about you. It really isn't, OP, and he really doesn't. He is so very, very much not a prize worth fighting for. He is a cheat and a liar, he has hurt you badly, and I very much fear that he's going to blindside you and hurt you far more in the future if you let him.
I have to admit that I don't really understand the concept of 'throwing your marriage away' by refusing to tolerate your H's lying, cheating and utter disrespect for you. As PPs have said, he's the one who's thrown away your trust and trampled all over your feelings and your relationship together. And leaving him wouldn't somehow cancel out all the years you spent together. The memories of when your marriage was happy and loving will still exist. The children you made together still exist. Leaving him doesn't somehow make all the time you spent together suddenly worthless. You keep repeating that you can't leave a nearly 30-year marriage and I genuinely don't understand why.
And as another PP said, google 'sunk cost fallacy'.