Breaking up with a mentally and emotionally unstable is it done?

My boyfriend and I have been dating on and off for 1and 1/2 years. I got with him after quite a bit of tumultuous relationship activity where I broke up with my ex of four years and my best friend whom I began dating left me for some ...girl in New York. I essentially went out with him because I was in an emotional upheaval and he was there. I do not have an emotional attraction to him and have not since I entered the relationship. It was a miserable mistake. I am 23 and he is 19...our mentalities are completely different.

I regret to say that I have cheated on him multiple times and we have broken up nearly a total of 10 times and still gotten back together. Every time I have attempted to end it he guilt trips me back. This guilt tripping consists of him curling in a ball helplessly crying and wailing and making suicide threats. On top of it all I am living with him since my step-mother essentially threw me out of my house.

With the guilt of the fact that he has taken me in and has been taking care of me hanging over my head coupled with his pitiful crying and suicide threats, I am left at an impass. He says that I am the only thing he has in the world...I feel responsible for his happiness (though logically, I should not. No one should place such a burden on a person).

He recently found out that I cheated on him (kissed...that is all) with a friend of mine that I had previously cheated on with before. He has (rightfully) told me to cut this person out of my life, however, I am in love (ish) with this person that I cheated on him with. This is something I can not and REFUSE to do. With 3 weeks left before I move out (into my new apartment) I am in quite a predicament.

The question being here is: how do I effectively break up with my boyfriend without him guilt tripping me back and threatening suicide? Is it right for me to leave him after all he has done for me?

Answers please and thank you.


Lost and confused.