Am I a bad friend?

Well I'm pretty loyal to my best friend. The sleeping around business I wouldn't get too involved in. Doesn't really sound like that is the issue though. Sounds like Vivian is being insecure about her now husbands past. If she was continually bothering my best friend oh yes would I have something to say. A one time thing.....I'd probably mention to her that I didn't think behavior like that was cool at all. I wouldn't typically hang out with someone who was that insecure anyway but I get the whole she comes with the package deal.
I would tell my bestie that I did tell Vivian I wasn't ok with it but again, you aren't trying to be shopping friends with this chick, just being mature about the situation since it's hubby's best bud and your marriage will always come first.
If Vivian couldn't grow some self confidence and get over it or tried to talk crap about my best friend to me then I would have to re-think joining the get togethers.

Oh God, what an impossible situation! Phil sounds like he should be castrated, and your friend should have listened to your advice. I know best friends can expect a lot of each other but in saying that your friend chose to sleep with him, knowing he's bad news, and I think if she disregarded your advice to start with, as well as letting him back in her bed, then it's her emotional mess to deal with and she can't expect you to get stuck in the middle.

If it was one of my friends I think I'd give them the "I don't like how she treated you, however because of my husband I have to see her and I'm sorry what happened but this is very difficult for me too" commiserating speech.

Castrated? That's pretty extreme there. :laugh: