I have more thoughts about you leaving him. Let me paint you a picture.
As soon as you leave, he will go to be with the OW. It seems counter-intuitive, but you actually want this to happen.
The sooner they get together, particularly the sooner they move in together, the sooner the honeymoon stage of their relationship will be over. They will settle into the banality of a normal relationship which is subject to its usual stressors. Arguments about chores and bills. Sex becomes routine. She wants a kid and he doesn't. He can't afford to take her on a holiday due to his spousal and child support bills. She wants to move states but he can't leave the kids. They both get diarrhoea and sh!t themselves in front of each other. The fantasy crumbles.
Your H, having not done the work, brings his lack of accountability and poor coping skills and massive entitlement into this new relationship. I'm going to wager that OW is similarly lacking. They spackle over their shallow relationship built on lies and lust with filtered Instagram posts about #truelove and #blendedfamilies and #bonusmom. This part stinks, but you are too busy building your fabulous new life to check their social media. The kids have two birthdays and two Christmases every year and they're cool with it.
A year or two passes. You have reached the glorious state of meh and no longer have any feelings about H except indifference. Your kids will talk about him and OW and you'll say "cool", "bummer" or "wow" without feeling even a little sting. Then! You hear word from the kids that H and OW have broken up in dramatic fashion - probably more infidelity on either part, throw in a suicide threat, definitely some sad sausage Instagram posts. Your H realises what a colossal, gigantic c0ck-up he has made. He comes crawling back with promises and regrets. What happens next is up to you...
