Most Helpful Guy
Many times you can determine genuine suicidal behavior. Most don't threaten it without genuine prior history. However as someone who has counseled this... you have to take every case seriously. He is already thinking out plausible methods and how it will effect you. At the very least he is highly troubled and not capable of a productive, loving, adult relationship.
At the worst, he is genuine. This change can be rapid or brought on by drugs and alcohol in the mix.
If he has access to this weapon, you have a responsibility to him and others to report it to the police and any other responsible parties (family, etc).
Sounds like he needs professional help. This isn't ok. Violence is not a bargaining chip. He should not put you in that situation. It's very manipulative and selfish. Walk don't run. If it happens again call the police. Be very careful that you are not alone with him. If he's upset or near that weapon especially. Protect yourself and others.
Good luck. Message me if you need more help.
Most Helpful Girl
I agree with most. He's bluffing. But you shouldn't overlook how he feels for you !! I'm not condoning cheating and lying but people make mistakes. Even so 9 years is a longggggg time , here him out. As you can see he's lost. You don't have to help him as a girlfriend but help him as a man (even though he cheated ) who stuck by your side. Let him be aware of how things just don't work that easily , like threatening to take your life , that's not gonna have you crawling back. But that is a definite scream for help. If your religious take him to a church or mosque. If not volunteer somewhere.
My prayers are with you. Good luck !!