Crazy friendship, not sure what to do... please give me advice!

(Names changed for privacy)

Growing up, me and two of my best friends Anne and Lucy were my best friends. As kids we were inseparable, although we did get in arguments frequently. Both Anne and I were closer with Lucy than with each other.

About two years ago, things started to go downhill. Lucy came out as gay, and immediately after started becoming very flirty with both Anne and I. She would come up and put her arms around us even after I told her that made me uncomfortable, she’d constantly call us hot and sexy and said stuff like “if you weren’t so far in the friend zone I’d have a huge crush on you.” When we tried to tell Lucy’s mom about the situation, we would get yelled at for treating her differently after she came out.

Now, this isn’t really the issue now (although I still am, and my bf is,VERY uncomfortable with how touchy she is), but this is the incident that brought Anne and I closer together. We started talking and one day, she told me “I shouldn’t talk about Lucy behind her back, but I feel like you need to know some of the bad things she’s been saying about you.” After a while we both realized Lucy had been using both of us, and that she was talking behind both of our backs.

The next year, we grew apart a little. I still told both of them almost everything, I was very depressed, self-harmed, was anorexic, and had a suicide attempt. The day of my suicide attempt (after the doctor and whatnot) I received a text from Anne. I had told both Anne and Lucy what had happened. Anne told me that Lucy had been texting a group chat full of four people I didn’t know or trust, telling them i’m graphic detail about my suicide attempt. Minutes later this was confirmed when I received texts from one of the girls telling me to try try again, and to use a gun as to not leave a mess for someone else to clean up. I was heartbroken.

This incident was months of not talking ago. Recently I decided to put the past behind me and move forward... but a couple weeks ago Anne told me about a lot of awful things Lucy has been doing still, that put her in therapy and caused her major depression. Anne doesn’t know that I decided to forgive Lucy, and that’s where the problem comes in. Should I forget about Lucy, because of the issues she’s causing Anne (now my best friend)? Should I tell Anne and hope she doesn’t get mad? Thank you so much if you read it all the way through. I know this is just friend drama but Anne is really in a bad place and I wouldn’t want to do ANYTHING to jeopardize her mental health anymore.