Hi everyone, 

So this is the situation: it was my birthday 2 days ago (go me for making it to 26) and I had a birthday party organised. It was a day rave and it was organised in August (bday in November). Anyway, about a year ago, I made friends with this girl at my old job. I quickly got sucked into her vortex of drama, and things became very intense between us very quickly. 2 months after meeting her, I am declared her best friend. She then got sacked, but we stayed in touch. 

As time went on, more and more red flags started to appear (rich coming from me who has BPD but alas) - she got into a relationship and was fine for the first 6 months, but then as soon as he did something wrong she would break up with him, get back together with him, etc, rinse and repeat process. Throughout this whole time, I served as her rock, and she would frequently unload all her emotional drama onto me. It got to a point where I felt I was in a relationship with her boyfriend! The worst one was when he had a couple of friends who were girls over and she freaked out, drove up there, took all her stuff, gave his key back and drove back down (3 hour round trip), only to get back together with him 3 days later.

When she went on holiday with her boyfriend, she had a massive go at me for not talking to her for a couple of days as I was busy and didn't reply to her within an hour. This is also an issue she has with her boyfriend, she would go crazy if he didn't reply to her texts for a few hours. This was one of the red flags. Another one of them was how the conversations between us were usually exclusively about her and her life and her problems. I ended up emotionally drained as a result. 

For my birthday, she was supposed to be coming over and going out with me and my friends who hadn't met her yet. A few of my friends had come from quite far away and were staying for more than 1 night, so I decided that they would have bed space. Two days previously, she was saying she didn't know whether she was going to stay over as she had a friend who was out in my neck of the woods in London, so I thought great, she could come out to mine, go meet her friend and everything would be dandy. I hadn't promised anything at this point. So I communicated this with her, and she effectively said she'd expected to share a bed with me (I was going to share with my boyfriend), accused me of not wanting her there, despite me saying she was more than welcome to stay, but would have to sleep on the sofa. She started off sad and then came back really angry, and accused me of fucking her off, upsetting her, all sorts, and then decidedly said, I am not coming to your birthday anymore, send me my ticket I am going to sell it and go out with my boyfriend instead. 

Over time, I began suspecting that she is a narcissist, as she relies on constant validation from a variety of supplies. I decided to block her on everything following her declaration that she wasn't coming to my birthday and declared me a horrible person for daring to suggest she sleeps on a sofa. Bear in mind that she would have easily been able to get home and she lives about 20 minutes out of London. I did say this but was told that was extremely rude of me. 

I am now going through the motions. I decided that blocking and ghosting was the wrong way to go about ending the friendship, so I sent her an email basically outlining my reasons for not wanting to be friends, but in a nice roundabout way. She replied within minutes and said it was all my fault because I clearly didn't want her there and she doesn't want friends who don't care about her wellbeing because apparently not giving her a bed is not caring about her wellbeing. She also said I have a lot to learn and can't go round treating people like they are not wanted anywhere which absolutely was not the case! 

I am now quite worried because I am expecting a fallout, despite me having cut all communication. I feel like she is going to try and make my life hell and start spreading lies about me. She's only met a couple of my friends (mercifully) and my boyfriend actually ended up telling me he didn't like her at all (which is saying something cos he likes everyone). 

I am currently going through the motions of being angry, being worried, being a bit scared and feeling guilty as though I've done something horrible to her. Couple that with the BPD, it makes for a very intense set of emotions and I have shit to be getting on with but can't because I am quite worried about this. 

Does anyone have any kind of experience in dealing with someone like this? If so, what happened? Were you able to deal with them? 

And, am I in the wrong here? I cannot shake this guilty feeling that actually it's my fault? Any advice gratefully received.