Most Helpful Guy
First of all you got to leave the guy and not think that it's your fault at all if he actually kills himself because in the end-he has control of HIMSELF and NOT you. Tell him "it was great getting to know you but things just aren't working out for us. You'll find someone that fits you better" (kinda a lie cause he is crazy but who cares cause he is being a complete Fukin asshole for threatening you with killing himself)
Also, maybe tell the dudes parents if you really think suicide is a possibility. It's not like you'll ever see him again so let his parents deal with his stupidity and now the responsibility is theirs and not yours.
Most Helpful Girl
Threatening suicide is the most annoying thing that some immature, controlling and manipulative people do. Since he was controlling during the relationship and used threats to control your actions you should get away now.
The #1 rule of breakups is stand firm. Don't be wishy-washy with what you want. Don't lead the other person on by trying to 'be their friend'. There really is no point.
The only thing a suicide threat does is tries to push the hurt that they are feeling onto you. It's a way of "getting you back" for the pain they are feeling. It's an immature thing to do. If your boyfriend has no previous suicide attempts you have nothing to worry about it was just a lie to try to make you feel bad.
The way to make a breakup the least painful is to just 'rip the bandaid off quick' one meeting to state your intentions and then nothing. Don't talk to them, don't email them, don't talk to their friends or family. Keep your distance and completely separate yourself from them. It may seem difficult and hard and curel but really, it's the only way to do it. Don't dangle any reminders in their face, don't lead them on, just completely ignore them. Seriously. It only hurts more and prolongs the hurt to lead them on. They need to get used to not having you around.
You are hurting too so you need to take some "you time" to sort our your new lifestyle. you may be thinking "i need to talk to him because it will make him feel better" when really you just want to make yourself feel better.
Seriously. You've broken up now sever all ties. It's the only way to break up with someone. Trust me.
Completely ignore the suicide threat (s). Don't let him think he's gonna get any response from you for it. If he keeps up with it - call his mother and tell her to deal with it, that you're not going to put up with it.