We've been together for quite a short period of time, 4 months now, yet I feel like I've spent at least the last 2 months wishing I never met her in the first place. 

She's in a very bad situation: she's afraid of sleeping alone and will basically stay awake until 6 in the morning, only to then sleep until late afternoon, she hasn't worked in a year and has almost run out of money, her family is shattered because she only lives with her mother (they're always arguing) and hasn't seen her father in 3 years because it is him who ruined her life.

Whenever we meet, she's costantly unhappy because she feels like we don't have enough time for ourselves, cries when I leave, she keeps getting angry because things never go the way she wants and loses her patience all the time, becoming very angry with me. I am a very calm person yet I don't really know what to say in such situations to make her feel better. 
When we don't meet, she needs to hear my voice because if we just text she says she doesn't recognize me. Then if she hears my voice she says its too different from the one she hears when we're together, we end up staying on the phone for 5-7 hours and after that she cries because she feels alone again. And most of the times she gets upset during the call, something goes wrong and no matter what I say she'll feel horribly.
 
This week, the plan was to meet all days from today to Sunday. We had planned to meet very soon today so we could do more stuff together (mostly sex, back on that later) but the company I want to work for has asked me to spend my afternoon trying out this job to see if I'm good for it. I told her this yesterday evening, she immediately felt alone, cancelled a meeting with an association shes part of (she's been doing this for months now and is barely active in that association anymore) and asked if we could meet immediately. I told her I needed to get some sleep (I basically sleep 4-5 hours every night because we stay on the phone or we meet) this led to some 3-4 very painful hours on the phone, in which she costantly cried and told me I don't care about her and that she's the most lonely person in the world. At one point she hanged up and then called me back telling me she wasn't capable of controlling herself and might hurt herself. She said she couldn't control her disorder, she wasn't capable of controlling herself. She did not hurt herself in the end but told me she was sick of life and should never have born. This has happened already, she cut her arm when in another situation I couldn't spend the afternoon with her.
She's hurt herself in other ways too. I cut my hair too short once, and then we met in the afternoon and went out to some big event in the evening. She felt very upset the whole time because I had cut my hair and said she didn't recognize me, during the event she then got a strong drink even though she never drinks. She did so because she hoped that it would make her feel better, perhaps. She immediately started crying and I had to keep her from falling to the ground. There was a live concert right in front of us so nobody heard her sobbing but I could, and she was also screaming very loudly, I was very scared. I've never heard anybody scream like that, not even in movies. After a while she started roaming the place, with me following her, whenever I tried to stop her she would tell me to leave her alone because she didn't know who i was. This is because she was drunk, yet the thing is this whole situation started because I cut my hair. 

She always feels like we don't have enough time for ourselves, or some privacy. She doesn't want to stay at my place because she hates my parents and calls them bigots (they are), so she wants nothing to do with them, and also suggests that i tell them that. Her house is very small and she lives with her mother too, so she needed some privacy for the weekend and we decided to pay for a room and spend some time there, basically for sex. We inevitably argued and she went crying in the bathroom, I tried to talk to her but could do very little while she got even more upset. We went back to the bedroom and I just bursted in tears, which made her feel even worse because she felt guilty, she told me she had always destroyed her partners emotionally and should just stay alone. Sex in general has become very problematic. The moment my penis is not hard enough she gets angry and tells me its not normal, tells me its not normal if I don't masturbate, gets angry with me because she can masturbate on the phone while hearing my voice while I don't do that, and interprets this as me rejecting her. Basically these things were never a problem in the past, now I really don't feel at ease doing these things with her.

To be honest, I don't feel at ease with her in any situation. My favorite days of the week have become those in which we don't meet, I'm scared of talking to her in the evenings because the smallest thing could make her very angry, I just don't love her and actually wish we never met. But I pity her and feel like if I leave her she will hurt herself like she's already done for something like not seeing each other in the afternoon. She's already tried to kill herself multiple times in the past. She keeps telling me i'm the best thing that ever happened to her and she already cries all the time because she hates herself and cannot change. She cries so much, once had a panic attack while we were on the phone. I really wish we never met and I don't think things are going to get better.

I'm a coward because whenever she cries I have to tell her that I'm close to her and that I love her, while it's not true. I'm afraid that the more I allow this to continue the worse it will become, we will just keep on hurting each other. I feel like I should stop this cycle by leaving her, though I'm afraid things won't be that easy, I don't want her to hurt herself, and I'm afraid I'll feel guilty for this, I don't know if I'll be capable of cutting contacts, I know a lot of people come back to their bpd partners out of guilt. Her ex has done this like 8 times, which has left her devastated and has probably reinforced her fears of abandonment.


EDIT: Thank you for your comments, I'd like to specify that she already takes enormous quantities of lithium to keep the disorder at bay, and should start meeting with a doctor in a couple of weeks. However she's already scared of this person because the previous doctor put her in a hospital to prevent her from hurting herself. Then she was put there again because her mother was afraid for her. Now she's afraid of telling how she feels to the new doctor because she doesn't want such things to happen again, so I don't know if things will change. She's had her blood checked and there's no problem there. And yesterday we met, she told me one doctor once told her that curing the disorder is hard in spring and that it could be possible that this stuff couldn't be manageable until the end of summer. I don't know if she has the willpower to actually heal, it took her 2 weeks to go get the results for her blood tests because she couldn't get up from bed in time and would always wake up in the evening. 

I know I have to stop this, but yesterday she was so nice the entire time we spent together, I couldn't tell her anything bad because this is not a bad person and I just hate the idea that I could leave her in her bedroom crying and feeling alone and vulnerable, scared to even get out of the house for a walk. I just feel so sorry for her, she's been crying so much it's heartbreaking. Every day she feels very sad unless we meet and she is so used to often see me, she's got nobody at home but her mom and they always argue, even when I'm there. I'm really scared.