AITA for cutting my best friend off

recently cut off my best friend for her uncomfortable and toxic behavior. She refuses to acknowledge it, mind you we are also roommates so it makes things very uncomfortable. Three of my other friends and I got together a week ago to confront her about this behavior. For context, the friend (gonna call her Amy) asked our other friend (gonna call her Gemma) for help to sneak in another friends room (gonna call him Grayson). Amy said she wanted to surprise Grayson, naked in his room during a party. This immediately raises red flags because Amy has made Grayson feel uncomfortable in the past. And on top of that another friend (gonna call her ella) has confided in Amy many times about how much she really likes Grayson. Ella and Grayson are kind of in a relationship right now while this is all going on. During the same conversation where Amy asked Gemma to help her sneak into Grayson’s room, Amy told Gemma that ella doesn’t really like her (which is also crazy because Gemma and ella are like best friends). Mind you, this is all one on one. So, obviously, Gemma tells Ella what Amy said. Gemma and Ella sent a very long paragraph to Amy explaining how they felt uncomfortable and betrayed. I was with Amy when she got this text message and she immediately freaked out obviously. As I was her closest friend, she immediately sought after me and repeatedly kept asking me if I believed her. If this was something that was out of the ordinary, I would. But, I can totally believe that Amy said, and did these things. Amy ended up going home that night and spam messaged me asking if I believed them. She also kept insisting that Gemma was drunk during their conversation so she doesn’t know what she’s talking about. the next morning me and my other roommate (gonna call them Ren) started talking about the whole situation. Ren had mentioned that Amy had made them feel uncomfortable multiple times and made weird comments about their relationship and sexuality. Amy was also convinced that Ren had a crush on them even though Ren is in a committed relationship right now. Ren and I ended up calling Gemma and Ella and asking to hear the story from their perspective. So, we got together and started discussing things. Slowly things started to be peaced together, and we realized that Amy has not been truthful about a lot of things in all of our friendships. For example, she started spreading things about one of our acquaintances, (gonna call them ash). Amy had told me that Ash had called them a Cunt and was just overall disrespectful. But, when I talk to Ash, Ash said the complete opposite thing ( Amy had called them a cunt). Gemma, Ren, Ella and I decided to confront Amy about this behavior. Before we had this conversation, Amy said to me “was our friendship even real at all if you seriously believe this” I low-key chuckled after she said this because WOW what a manipulative thing to say. Amy ended up denying everything and claimed that Gemma was just drunk and didn’t know what she was talking about. She also claims that she never liked Grayson, which is something I know is a lie for a fact because she’s told me she’s liked Grayson. This isn’t just a one time behavior for Amy. This has built up over the past year. I’m looking back at our friendship and realizing how many times she probably lied and used manipulation tactics to my face. Also, a couple of days ago I asked to speak to her because I didn’t want things to be awkward with our other roommates. She told me “you made your bed now you lie in it” and “ I can’t believe you laughed in my face”. I felt bad at first because she has no friends left, but honestly, I have no sympathy left. Her behavior has been a pattern and many people are realizing it. She had a fight with our other friend last year (gonna call her Alex). And I personally believe she handled the whole situation very poorly and spread gossip and misinformation. Also, she would blow up in my face every time I mentioned that I wanted to hang out with Alex. It felt like she was forcing me to not like Alex, even though I really do like Alex. She would constantly ask me if I didn’t like Alex and gossip about Alex to me. It always felt like I could never say I liked Alex so I would tell her I didn’t like Alex (which is something I’m very ashamed of and I know I shouldn’t have done, especially because I knew I was lying). She’s now hanging out with Gemma’s ex best friend and ex boyfriend which also has me baffled (because Gemma has told us lots of crazy stuff involving them). Amy has always given me a bad gut feeling, but I ignored it and now I’m realizing I shouldn’t have. She continues to deny all of this stuff and honestly that makes me feel a little crazy. While she also preaches how much she hates liars, but looking back it feels like projection. A lot of our other friends also have problems with her for different reasons. I honestly cannot continue being friends with her. It goes against my morals and values. Does anybody have any input?

On top of losing a close friend of mine I then find out my dad has cancer. It feels like I am down and Life is just beating me to a pulp.

TL;DR: my best friend has lied to my face and my friend’s face multiple times and continues to lie. She has done many gross and uncomfortable things to many people. I’m done with the friendship and just seriously need advice.