Depressed, Possible BPD? Narcissistic? Ex Girlfriend Left Me

[Possible triggers for BPD or NPD persons. Moved this thread to the Significant Others, Friends and Family Forum, leaving a shadow thread in Relationships for continuity - mod Orion]

6 year relationship. Tried killing herself January, alcohol abuse, cocaine abuse. I stood by her through thick and thin. Put up with emotional and verbal abuse for months. Typical things where 'you don't care about me' 'I hate you' 'your a f**cking p**ck' 'what have I got to live for' 'you'll all get over it if I kill myself'. She'd be extremely paranoid, questioning me over and over about trivial nonsensical things. She'd repeat herself 3/4 times in a conversation. I paid her cocaine debt because she begged for my help. I do this and spend 2 weeks nurturing her, cooking her good food, walks in the fresh air, making sure she got enough sleep, after one binge to many. She's was on citalopram (not sure if she still is). I take her awayr for her bday at the end of these 2 weeks. Spoil her rotten Tells me how much she loves me etc . Everything was great. More in love than ever. . 2 days after returning home becomes distant. Says she wants to be alone, she loves me, I'll never lose her she just needs space. Then find out there's another guy and has been for a while. I confront her at her home after she dumped me by text and ignored my calls for s week. She laughs at me the whole time I pour my heart out and really pays little to no attention to what I'm saying. Looking in people's windows who she knows etc. 'I can't believe you've come here' she said laughing. I return home heartbroken. She says she loves me with all her heart and always will, but 'not like that'. Cop out excuse for her new guy. She's still sniffing cocaine, drinking, not daily I doubt but regularly. Her new boyfriend is living at her mother's house with her and has been from near enough the beginning. I heard her brother owes money out for cocaine and attacked her mother. I text her to make sure she's ok and her mother. No reply. Ignorance. Will it last? Shows traits of bpd? Narcissistic? Never had an apology or genuine admital of guilt. She threatened to commit suicide many times over the phone. Be it by text or by phone call.

I'll outline her behaviour over the years together.

- very intense first few months, madly in love, me 17/18 her 16/17. Moved into her mother's house within a few months (young, dumb)

- strong sense of ownership from her. If I went out with friends I was picking them over her, if I didn't come back when I said I was all hell would break loose, she'd ring me every 10 minutes asking me where I was etc

- chronic cannabis habit from her. I smoked, but it wasn't a problem. She had terrible mood swings, emotionally unstable. Her father is in a home from drinking himself to dementia, she has seen her mother be abused, im almost certain she has been abused herself but she wouldn't admit that

- she quit cannabis. Doting girlfriend. Did my washing, cleaning, made me sandwiches. Typical girlfriend stuff. Still always seemed like treading on egg shells. You had to be careful what you said and who you mentioned for fear of her flying off the handle

- if I mentioned things I liked or people, she'd 9 times out of 10 demonise it or them. Or quite plainly say she couldn't care less what I was saying.

- Over our last month's together (Depression started in December) suicide attempts (taking 60+ paracetamols on 2 occasions within 2 weeks) alcohol binges, to the point of blacking out, erratic cocaine use. These are just the things I know she was doing. God only knows what else. She'd ring me saying she was sad and didnt no why. I tried my best to understand and console her. Sometimes I'd deny depression existed and insisted there must be a trigger. She insisted it just happens. I put up with her verbal abuse, once or twixe when drunk she became physical. She knew how to push my buttons and get me angry to the point where I had to walk out a few times. Everything when she left was so much improved. I'd spent 2 weeks keeping her sober, getting her sleeping pattern in check as she hadn't slept properly in months
NOT one sign there was another guy, not one sign she felt any differently about me even though when she ended it by text she said she'd been feeling like it 'for a while'. She was in fact closer to me than ever. She made a point of staying the night we got back from her birthday weekend away, knowing she wouldn't see me for a week due to work commitments. She made sure she stayed that night. We woke up hand in hand like most times and that was the last time she stayed at my home.

I really need some advice on why she behaved this way and still continues to do the same.