How should i handle the situation

Hi, There so theres this girl and we have been dragging the relation since july, 2014. Thing is that she is very very very suspicious all the time. If im on waiting for like even 10secs and she calls me in between she gets suspicious. Physically we come in contact like once in 3-4 months and she has been physical with two other guys before coming in relation with me. I can tolerate that but when she is suspicious she gets ferocious and i am also short tempered i also get furious then she bloody starts sending me texts of committing suicide it gets very very ugly she irritates me so much i feel like killing myself sometimes. i have to send screenshots of my call list to her then also she just doesnt believe. i have been trying to split with her since then and everytime she just freaks me out i get scared and i am back to square one. i have told her calmly also that it will not work out b/w nus ever she but she just doesnt understand. she says i love u and all that then i ask whatever she did with previous boyfriends physically wasnt that love?? she has no answer then then when i get furoius she starts crying and scaring me with death threats. Please guide me how should i get her to leave me and any legal action if it can be taken. the thing is i just cant b with her anymore even for a single second. and this fight is happening everydayyyyy. please help