I can’t decide what to do.

I had two “friends” at high-school. One of them was a fake friend (towards me) and disrespected me and left me out without the other friend knowing. I’m now in university and still in touch one of them (the friend who doesn’t know what happened between me and the fake friend). We’re not too close but in good terms with her and get along well. She tells me she enjoy conversations with me so do I.
She still has no idea what happened between me and the fake friend and she still is friend with her, they’re close and they’ve known each other longer than me and she’s closer with her than she is with me.
As I said I enjoy conversations with her and I love her. I’m currently too lonely and don’t have any friends at all because I wasn’t in a good mental satate for a long time so I wasn’t able to make new friends in that situation. And I don’t want to cut the only person I enjoy talking but at the same time it doesn’t feel right to be in contact with someone who is friends with a wrong person.
The fake friend (at least she was fake towards me, I call her that in order to make it clear who I’m talking about ) was someone who was hated by many people at school because she had done wrong to some others as well. I didn’t
know that she was a such person’ didn’t witness what she did but people who she had done wrong told me some of the things she had done to them.

I don’t know if my friend knows about the fake one’s shitty behaviors or not. I assume she doesn’t because I think if she did she wouldn’t stay as her friend. Because my friend doesn’t seem like a bad person at all. But as I said that’s just what I assume. I don’t know the truth.

I sometimes worry while chatting with my friend that she brings up or mentions her friend who was fake towards me.
Because I don’t know how to react and don’t have much to tell good about her.
Should I cut my contact with my friend or shouldn’t I?
Or is it normal that I’m still I’m touch with her after what her friend did to me?
What would you do?

Sorry if it’s not the best subreddit to ask this .

I hope things are clear enough .