Should I [19/m] blow the whistle on one of my former friends[19/m].

First of all I am sorry for the title, didn't know what to put in it but I think it makes sense.

Alright, so last year I started talking to this girl that was my friends girlfriends friend. Stuff started to get serious, thing is that I did never ask her out. we had just met at a couple of parties.

Why?

Because my friend and his girlfriend had told me that they hated her for a bunch of reasons and that she is a psychopath and this and that. As far as I know she is none of this, well it doesn't really matter anyway.

I really wanted to ask her out and really get serious with her. This made me do the opposite. So after a while of just talking ofcourse this to-be realtionship went nowhere.

Stuff happened between me and my friend and now we don't talk anymore. The thing is that I can't stop thinking of this girl that I really had something going with and that she doesn't know for real what her friends says about her.

So, after all this confusion about friends all over the place, to the question: Should I just call her and tell her how everything is? I feel that it's the morally right thing to do but I don't know honestly.

If there is anything I have to clarify, just comment it.

Thanks!