[Usernames Suck]

This guy doesn't really sound like a good person that you'd want to be involved with! You're better off without him, frankly. Just try to ignore him and go on with your life as best as you can. If you need to put time into something like crying or processing what happened, I recommend trying to find a safe way of doing so (like writing an angry entry in your diary or listening to music). He's not worth it. Hopefully your friend will realise this too before she's in trouble.

As to your friend turning people away from you, try to ignore it as much as you can. I think that if people see that you're going on with your life and not engaging in drama they'll be more interested in the truth rather than gossip, and they'll see you're not trying to go against her because of a guy that isn't great for either of you.