how do I help my depressed boyfriend

okay so basically me and my boyfriend have been dating for awhile and he struggles a lot with his mental health and vents to me a lot

but the problem is I've struggled with my mental health my entire life and don't know what I'm supposed to say to him or how I'm supposed to help him

earlier today he was talking about killing himself and I didn't know what to do but I was scared bc I rlly don't want him to do that

we're both minors so idrk what I can do