Should I break up with my girlfriend?

I think our relationship might be coming to an end after 3 years. It mostly has to do with arguing and that she can be extremely stubborn for no reason. Some of the arguments that she starts yelling at me about usually just dont make any sense (like I said something the wrong way on the phone). But is it normal to feel nervous about breaking up because you dont want to be left alone and you'll have to find somebody else? I feel like theres so much put into this relationship, that I dont know how I could end it. We've talked about it and she understands that she gets really crazy for no reason. But she says she cant help herself even though she really doesnt want to be yelling. She started hysterically crying because shes sorry that she puts me through so much. So basically, she wants to stay with me but feels that if she were me, she wouldve broken up with herself a long time ago. Does anyone have any advise as to what I should do??

Also, we've been through these conversations before and everytime she says that she's really going to try controlling herself from freaking out on me