I need advice badly

I met this guy while he was on vacation in my state. We spent a few amazing days together. We would go walking on the beach. We went out to dinner and saw a movie together. We sat at a park and would talk for hours. It's definitly love. BUT my family won't have anything to do with him. They havn't even met him but they "don't like him". I'm in FL and he's from HI. We've kept contact online and via phone; he and I have even flown back and forth to visit each other. I love him with all my heart. We hit a rocky point in our relationship, like all couples do. We were both stressing over us not being together in person (we've been together for over a year).
THEN
I met this guy in one of my college classes. We got together outside of school. I ended up having a crush on him. I couldn't help it but I sort of developed feelings for this guy. He was cute, sweet, and my family loves him. His family loves me too. He has preteen twin sisters that think the world of me. I've grown attatched to this guy and his family. I thought that maybe I could get over my Hawaiian love and maybe find happiness with my Florida boy.
After a few months, he (Florida boy) revealed his true colors. He's had a history of suicidal issues, has had issues with his behavior when he was younger, and has ADHD. He's taken medicine; it doesn't help. He's been to doctors but won't talk or tell the truth. Any little disagreement we have, he turns into a HUGE fight. He's even tried killing himself and said he'd kill himself if I left him. The other night we got into a huge fight after I asked him to turn the volume down on his video game because it was so loud, I could here it from the other room and it was almost 3am and I was trying to sleep because I had work. We argued to the point where he said he was going to kill himself, he pulled out his knife and I tried to take it away, he pointed it at me and said "No. Touch me and you'll go first". I'm scared everytime I'm around him. I know he can't hurt me because of my background, but I can't be with someone like that.
My family likes him (they don't know about his other side). I love my family and if I move to Hawaii to be with my one TRUE love, I'll never get to get to see them again because they will disown me. That's just how my family is. If I stay here, I get to stay with my family and my Florida guy's family and I would have to pray for a miracle. I don't love him (FL) like I love Hawaii guy. I can talk to my Hawaii guy for hours on end about everything and nothing. Florida guy... we're just not deep with our conversations. The deepest conversations we have are arguements. My Hawaii guy loves me unconditionally. He respects me and if we get into an arguement, we always work it out. He and I can relate so well together and I feel as if sometimes, him and God are the only ones that understand me. Florida guy severely annoys me 24/7. He's vulgar and lazy. Had I known he would turn out to be like this, I would have never spoken to him.
But I'm now stuck. I still care about him as a person. I don't want to hurt him. At the same time, I don't want to hurt my Hawaii guy or myself.
Basically, it's either move to Hawaii, be happy with the one guy I know I can marry and spead the rest of my life with but lose my family OR stay here with my family and my Florida boyfriend but lose what matters most to me, next to God.
I really don't know what I'm going to do. Any advice? What would you do?

Thank you Daniel for your words of wisedom. I guess I just needed it to hear it from someone. I don't have anyone I can confide in or talk to for support over here really. Hopefully, my family will eventually come around. If not, I'll still have my Hawaii guy and his family. Thank you so much. =)