hi there, as i was reading this, it seemed like you had written one of my problems for me.
my ex best mate also has found himself a psycho girlfriend.
They've only been together for three or four months but already he has told me to tell me to stay away from him, on her say so. I threatened that he'd chuck me over if i go near/text/email/phone him again. Thing is, she's never met me and there its completely weird that she has this grudge on me. I dont even know what she looks like!
All our mutual friends hate her and she is a serial liar too, lies about stuff that is so obviously bullsh*t that they cant believe she actually said it.
He also started to ignore those mutual friends now.
From my experience, the best thing to do it stay away from him all together, like everyone else has said. Because the last thing you want if for her to have more ammo against you or him to hate you for ruining his relationship. He may never get over it. He may be like my friend and desperate for attention and love, and she is offering that, so he wants to keep hold of it, no matter what. It is truely difficult, to hear horrible things from other people about how he is, and not be able to do anything about it, but it is his life, and his life to mess up to what ever degree he wishes.
One day she may realise what she is doing and get help. We both hope for this.
I am still at the stage where i cannot forgive him what he has done. but all i can be thankful for is that i have my other friends who have been there for me through this and have cheered me up.
I am sure that you have the same kind of friends.
If you believe in Karma you will be ok! eventually

chin up