I had a very close friend with BPD. It was hard, but I loved her lots.
She would put herself above all people, even her DP. I remember my sister and I being silently shocked when she ordered food to my address, didn't offer anybody else any, then handed her DP the remains, after he waited patiently.
My DH died recently, and she made it all about her. She wanted a lock of his hair, when I went to see him at the funeral parlour. She was going to get a tattoo in honour of my husband.
She turned up at the crematorium, dyed black hair, complete with daisies stuck into a weird Geisha hairdo and matching black fingernails.
My DSis remarked it was odd that my supposed friend had only come to see me once, in the 3 weeks between ddDH's funeral.
She would slag off what I was studying and pinch my arms hard enough to leave bruises, if we went out for a drink together and a bloke came over to talk to us. Of course I pulled her up on the pinching, her response was that she only did that to people she liked.
She once told me (whilst v. pissed) that she had attempted to seduce ddDH when we were first dating, and I had just joined his circle of friends (which she was one of) and he turned her down flat. ddDH was too much of a gentleman to tell me.
When ddDH bought a house together, she was very drunk bouncing around on our new bed and landed on my head. Her partner asked her to be careful, as she could have broken my neck. She later tried to strangle him and told him she wished he was dead.
One birthday, ddDH had made reservations for dinner. She rang me in a state, and said her and DP had been arguing, and she was self-harming. I cancelled my birthday dinner, and I asked ddDH if he would pick her up, and bring her to ours. She rang her DP, and the row carried on at our home, then into the street, with her kicking all my neighbours' cars.
We're no longer friends.