Relationship Issues

Hi everyone - this is my first post and is probably going to be a bit of a rant so I apologise.
My girlfriend and I have been together 3 years and both have mental health problems (I have Bipolar type 2 and borderline personality disorder and she has a currently undiagnosed condition but probably a personality disorder of some type, possibly ADD and depression). We live together and recently our relationship has been an a bit of a nightmare. After 11 years of me being up and down mood-wise, self-harming and overdosing a few times I finally feel relatively normal (due to a great psychiatrist and medication). Unfortunately my girlfriend's mental health problems seem to be spiralling out of control and I'm not sure how to deal with it.
Recently she's been self-harming (not badly enough to require hospital treatment or anything) and a few weeks ago she took a small overdose and then rang me (we had had an argument and I'd left to calm down). I had to call an ambulance etc etc and she was fine in the end. In the past 6 weeks I feel as though she's been extremely bad tempered and is taking it out on me. Every minor thing ends up in a blazing row as she just cant leave it alone. I try to walk away etc but she stands in front of the door and continues to have a go. I literally do not know what to do. She calls me selfish etc etc and cant seem to understand how her behaviour makes me feel. I've always tried to be supportive of her but I'm really struggling as the relationship is having a massively negative impact on my own wellbeing and mood. She says this is my fault as I'm selfish and shouldnt rely on her to influence my mood. I really love her but I'm really struggling to deal with this.I just wondered if anyone had been in a similar situation?

Is it possible she is Narcissistic or Sociopathic and abusing you for attention or supply? Sounds like you in an abusive, manipulative relationship....

My advice would be to write her a letter, tell her how you feel etc its obvious you love her or you wouldn't stay.

Since she is unable to have a talk without erratic behaviour write everything down and give it her, then leave her to read and digest what you have written. Obviously there is something not right with her ATM and if she can't talk ask her to write you back.

All the best and don't forget to say how much you love and care for her point out all the positives don't just be negative.