Title kinda gives the TLDR, but no doubt more information will be needed. My FP, prior to wanting nothing to do with me, occasionally tried to help with my mental health but they were doing it to the detriment of their own mental health and now want nothing to do with me. They’ve blocked me on everything and in person they don’t talk to me unless they need to. I don’t know what to do anymore and now feel shit about everything. 
I think they hate me and are lying about why this is happening (they said that hanging out with me had association with them trying to help my mental health, which makes their own mental health bad. So they don’t want to hang out anymore at all), they also seem a lot happier now (when hanging out with our friends, who also now want nothing to do with me at all)

At the time I didn’t know they were my FP (I didn’t know it was a thing) but looking back on everything it’s quite obvious. They don’t know that I have BPD and I doubt they’d care anyway and I also can’t tell them as they hate me and don’t want to talk to me. I don’t know what to do