Are you still involved with the kids? I tried to look back at your older posts. The stories are starting to blend together for me. I do know you both came into the M with kids.
Anyway, if you're still involved with the kids, you are not "out of the picture". Even if your kids are grown, they'll still graduate HS, college, get married, have kids, grandkids. WW/WAW forget about that stuff.
Stay out of her new R. She'll screw up her own. She's on the WW rollercoaster and the new BF doesn't sound like he likes rollercoasters. From the short description, he may have wanted a mom for his 3 kids after his wife died. Maybe he realized that you can't have a wife w/o drama and that's why he divorced mom 2.0. Maybe his kids hated her. It doesn't matter. The OP is probably ready to hit cruise control on his life and that's why he doesn't want drama.
Seriously, if the guy doesn't want drama... WTF was he thinking hooking up with a Ms. Kramer. I can't think of anything more dramatic than a WW.
Cheaters are stupid and selfish. Those that hook up with cheaters are no better.
If you have a sick sense of humor like me. You could have fun and register them for wedding gifts at all the major department stores, Amazon, etc. Congratulate them on FB, spam everyone you know with an awesomely photoshopped wedding e-vite. The reception should be at Chuck E. Cheese and it BYOB (plastic bottles only).
Actually, that may be bad advice. It's not DBing. It's just funny.
M:42 W:43 T:14 M:10 S:9 D:5 W filed 12/22/14 EA 12/31/14 PA 4/10/15 D final 5/13/15