This may sound like tough love, but you were not brought into this world to be his salvation. He clearly has issues, and should be in long-term treatment, but destroying your life is not a way to improve his. Honey, you are better off alone than in this relationship. block his number, change your number if you have to, it sounds like you have supportive parents, engage their help if you need it. There are resources for him, and I doubt he is truly suicidal (most people who are don't advertise it so openly, hence the suicide epidemic, in his case it sounds like dramatic ways to draw your attention any time you distance yourself).
I have had both an emotionally abusive relationship, and a relationship with a man who loved, respected, and treasured me. They are out there, they do exist, don't think this is all you can ever have. What you are feeling is not love, I'm not a doctor but it sounds a bit like codependence combined with pity, and guilt that he keeps making you feel.
Hang in there, I wish you luck, and send you many hugs dear.