Congratulations Elsa!
And you're right - if your ex couldn't simply refrain from recommending the group go out to eat someplace he knew you didn't like - he didn't care for you the way a spouse should. And no, you couldn't have done anything in counseling to save the marriage if he was sleeping with OW during.

The karma? You're marrying a hot guy, while his affair partner didn't think enough of your ex to blow up her marriage for him. Neener neener neener!

I'm sure, now that you have a good guy that cherishes you, you can see the ways in which your ex was not a good husband. Enjoy that. And I hope your new hubby's ex wife leaves you alone. (Be prepared for one or the other of your exes to pop up right before the wedding. They like to think you're waiting on the Plan B shelf).