I broke up with my best friend who has BPD and I’m still traumatised after months. I’d love for you guys to recommend ways to heal if any of you have unfortunately experienced this. Here’s a little background...
It was a gruelling and chaotic 4 year old friendship. It started off as the perfect friendship, and she seemed to be a godsend in the hardest times of my life. Misery did love company as we heavily depended on each other to pull ourselves out of our woes, at least that was the intention. At first, her faults seemed negligible and her frequent hot headedness was not unordinary. Her reactions to every situation seemed perfectly understandable given how unhappy she was with the circumstances of her own life. 
I made it a point to support her and encourage her to take on a positive outlook toward everything. I was there for her during the periods of deep sadness and unbearable grief she experienced because of the breakup with her boyfriend. After two to three months of caretaking like I had never done before, I was puzzled to find that her grief and unhappiness only intensified. 
So, I decided to work harder for her because I knew there was light at the end of the tunnel somewhere. At about the same time her expectations of me doubled and kept growing. She would be mad if I wasn’t there there when she wanted to cry or when she wanted my presence. There were moments when she was unreasonably furious at me and convinced me that I had committed a grave mistake of some kind. She began to publicly humiliate me and later call to tell me I mattered more than the whole world. 
We began to have nasty arguments every few days. She was always quick to remind me how ungrateful I was to her for introducing me to her friends (who ended up being my very goods friends), and for saving me from my sorrows when I needed it. She hated that I had other people in my life I cared about and she had built massive dreams for us. She wanted me by her side as she went on to fulfil her dreams and had convinced me that they were my dreams too. 
I blamed myself for being such a terrible person to her and put myself on the job of extra caretaking because she was my best friend in the whole world. As a result, people began to distance me, I didn’t do well in college, my self-esteem was at an all time low and my boyfriend left me. I was at the lowest point in my life. 
I was neck deep into caretaking by then and I attended to her like a soldier reporting to duty. Ignored all the disasters in my life and endured the torrents of stinging abuse day in and out. I knew deep in my heart that she needed help and the others failed to notice it. I dreaded the idea of politely suggesting it to her mostly because I was terrified of her. 
They were the worst years of my life but I wish I could have helped her. 
When the pandemic hit, we were forced to stay away and I had ample time for myself to revisit my feelings. I realised I had regularly had panic attacks whenever she demanded my presence. I finally began to see how she had managed to manipulate me into believing that I was not enough. I was incredibly depressed and I needed help. It was only then that some people I knew mentioned that she had BPD. I read a lot on how to stop being a caretaker and reclaim my life. I knew that I had to detach myself from her to heal and regain confidence. I felt crippled and devastated. I felt heart broken for not being able to help her but I was also angry about how damaged I was. 
I had read somewhere that one cannot forgive until one addresses one’s pain head-on. So I communicated as politely as possible and conveyed all my hurt without assigning any blame to her. I also apologised for not being able to understand her. In response, she lashed out at me and told me that I had betrayed her. That was the last I heard from her. Months have passed since, and I still have panic attacks at the sound of her name. I will never know if I could have dealt with it any other way and I keep telling myself that I did what I could.