i’m my ex’s fp and it’s starting to get suffocating

TLDR at the end.

we’ve been broken up for almost 7 months now and i have stayed because i still love her and i haven’t completely moved on due to our setup of basically still being each other’s everyday. she’s a country away so we spend a lot of time calling and playing together. she told me about her bpd early on and i read up on it. she used to take meds and was in therapy but isn’t anymore. we have gotten into many arguments, but just last night we argued over my best friend of 3 yrs who just broke up with her bf of 2. he was also my best friend.

bsf asked me if we could call and hang out so she could cry. one of my ex’s main triggers is bringing people up in the middle of us hanging out. this is my mistake as her fp. i still did it because of course, i wanted to hangout with my heartbroken bsf who has literally been there at every high and low of my life. when i told her, she went quiet and i could tell her mood dropped. in the end, me and my bsf didn’t hang out (not cause of my ex) but my ex and i fought about it later on.

she got upset with me because “i don’t want to hang out with her anymore” and “i’m leaving her again” (a couple weeks ago i tried to cut contact with her bc our setup was affecting my mental health bc i couldn’t move on from her). she keeps saying im choosing my bsf over her and all, and that by hanging out alone specifically with someone else it feels like im abandoning her. she straight up told me she doesn’t want me to hang out with other people (alone) and i don’t know what to do. i have already cut of so many people in the past for her and i’m starting to feels suffocated because i feel like i have to choose between them.

tl;dr my ex has bpd and i am her fp. it’s starting to feel like she is becoming too controlling of my other relationships, especially with my best friend i am starting to feel suffocated. she does not take any meds or therapy currently.

please help.