Dating someone with depression

Everyone talks about depression but now how it feels to date someone with depression. The repeating cycle of emotions that your significant other has to deal with. I’m 6 yrs in my relationship and this may sound harsh but I am starting to get annoyed. Hear me out pls! When we get in heated arguments he says things like “I can’t wait to just die” and” I hope I wreck on the way home” and things of that nature. He talks about how no ones cares and all this stuff. In the beginning I was very understanding and always talked him out of it (or thought I was). Now 6 yrs later the same thing it’s like he’s crying wolf at this point. He’s threatened to kill himself so many times it’s not even funny. He even locked himself in the bathroom with a knife which I took very seriously then got mad that I called the police and said he wasn’t serious. I can never tell whether to take his condition serious or if he just wants attention. I forgot to mention we have a child too. I’m just frustrated and fed up but I feel like if I leave in the asshole who left someone to deal with depression on their own. I’ve also told him multiple times to see a dr if I’m not helping and he refuses. Idk if he’s scared to go and the dr tells him he doesn’t have it and feels worse or if he just wants to handle it on his own.