I'm stunned that my best friend cheated on her husband and they're not in an open relationship. I don't even want to be friends with her anymore.
Cheating on your spouse is bad, but why don't you want to be friends with her anymore.
Yes I lost my respect for her
Well, your friend did show she isn't trustworthy by cheating on her husband. The open relationship thing is just something she should have been honest about wanting and there's nothing wrong with that, but she showed she isn't trustworthy and it's okay to not want to be her friend anymore because of it. Hopefully she'll learn from that mistake and maybe you can be friends again in the future.
I think it's okay to be prudish about your friends cheating. I can't have those types of people around me.
If you feel like this is really something that you can't tolerate, then it is best to part ways with your friend. However, everyone makes mistakes sometime, so you should consider eventually forgiving her.