suicidal girlfriend

Ok Im normally quite good at handling things quite well on my own but I’m stressing over this a lot. I met a girl online 3 months ago & we hit it off really well. We chatted on the phone for hours about life etc. She is 36 & had had a tough time of it. She had been adopted as a kid, raped by an ex boyfriend and beaten up & last year when she thought she had finally met the love of her life, he decided to hang himself in the bathroom for her to find because they had had a row. That last episode put her in Hospital for some time as she had lost the will to live & when I met her she had been put on antidepressant, had a beareavement councillor & was just starting work again as she was getting much better. She was quite possesive & very suspicious when I said I was out with friends but I thought that would pass as she got to know me more. Anyway, I went over to see her & we spent 4 great days together. When I came back she got much worse possessively. I tried so much to reasure her but it didnt seem to work & she kept sending me snidy texts & making me feel like crap. Eventually I couldnt take much more & more or less ended it. She text me to say she was going to kill herself & I was on the phone like a shot. I eventually calmed her down but then felt trapped in a relationship I didnt want to be in. Well today she really started sending me snidy texts because I didnt reply to her in time & because I was going out with my friends tomorrow & I got angry & steared the conversation by text around to ending the relationship. She has basically, not in so many words threatened to kill herself agin & I dont know what to do. I have tried to be so reassuring because I still care for her (just cant take all the snidy remarks and jealousy). She just texted me now & all it said was ‘no more’. Im crapping myself she is going to do something so stupid. Im hanging on to the fact that she said she would never put anyone else through what she went through when her ex hung himself but she also hinted that if she did kill herself I would never be told (as nobody has my number over in northern ireland) or have to see it.