OT, I did feel more anger towards OW in the beginning. Safer when you're trying to reconcile with your WAS. But as time goes on, I would see them both as equally responsible or culpable. The only reason in the world I want my kids to associate with their dad is that he is their dad, they love him, and that's how that works. But OW is not their parent, and so I have not 1% feeling she should be around my kids.
I think a lot of the OW's are either morally-deficient and/or messed-up, not making them good role models or people I would want my children to associate with. (And I know my X is the same).
The OW in my case has been married 3 times, and cheated on her 3rd with my H. She allows her young daughter to drink, and people that work with her says she sleeps around with all the guys in the office. I don't believe I will ever want her around my children. Her children also are psychologically messed up: anorexic, her one dd (the one she allowed to drink starting at 12) I've been told by friends of mine who know her well say she is the nastiest brattiest kid they've ever met. It horrifies me that my kids are hanging around with people like that. Horrifies. And yes, I know my H is like that now too.