How can I help my bf get through his depression spell? He told

If it's so bad that he's considering suicide, he should really seek professional help. What you can do is supporting him so he feels himself valued and appreciated. Why is he depressed?

What are you doing dating a 17 year old? Are you the same age?

He's stressed about a lot of things but I'm not sure what triggered it.
We're about to be the same age in a month

The fact that he set a date probably means he isn't that committed to it. If he really wanted to kill himself, why would he wait ? At least that's how it was for me. I told myself i would kill myself in x amount of time if i wasn't happy by then. But here i am, not dead, and still not happy, but oh well. I think by setting a date he doesn't actually want to die, that he wants to see what can happen during that time, that hopefully he finds something worth living for. Again, just my 2 cents. If anything, i would just accredit his behaviour to teenage angst.

This could alternatively be some cheap cop out to break up with you. I obviously don't know anything about your relationship, so it's hard to say. But breaking up because he says he's going to kill himself ? Cmon...

Yeah I could see that too, I've tried planning it just to see if I end up being happy in the end.
I think if I just keep showing him that I'm here for support then I'm sure he'll come back eventually