I think my friend has borderline

Hi, I am pretty sure my best friend has borderline personality disorder. A few days ago me and my other two best friends talked about how quickly I change around this person. I also started to reflect on how my opinions change very fast when I’m with her. My whole personality in fact. She often convince me that these other two best friends doesn’t like me as much as they like each other and that they are toxic. I change my whole way of thinking around her. She has depressive episodes and drags me with her when it happens. I’ve been manipulated so many times without even realizing it, even when it was obvious. She tells me that I’m the only person she can talk to and later tells my other friend the total opposite. She tells me she loves me and behind my back she talks shit about me. It’s not only me but my whole friend group. I become really toxic against everyone else when I’m with her and this has been going on for years. Right now I feel like I want to leave her but at the same time I just want to be with her. She’s my best friend... She asked me if something was wrong today and wanted to hang out. I told her I needed to study but it’s not like I can ghost her either. I don’t know what to do and if someone has gone through the same thing or have tips I would really appreciate it. I know she will continue to manipulate me and I don’t know what to do.