Your boyfriend has gone through a tramatic experience. If he has attempted suicde already, he is in dire need of some professional help. Try to encourage him to seek help. If he refuses, you have a difficult decision to make. His suicidal thoughts are the first thing that must be dealt with, then he can deal with the issues that caused his suicidal thoughts. My advice is to contact a suicide hotline and tell them what is happening. They will be able to point you in the right direction.You may feel as though you are breaking violating his trust in you. Don't feel that way. The trust that he has in you can always be built back up. When he feels better, he will understand that you just wanted to help him.
Hannah, there are many people out there who are trained to deal with this stuff. You need some help with this. You can not be expected to take this on by yourself. I would also advise you to tell your parents whats going on. You too, need some support in these circumstances.
Good Luck and may God bless both of you.