How do I tell my BF who I really am

So I'm 16 and my BF is 17, both juniors is hs. We been dating for almost 7 months. I'm quite happy with him but he doesn't even know the real me. To me I'm that pretty confident girl that's loyal and always seem happy but the truth about me is I'm suicidal, I have anxiety(which he knows about) I'm never really happy. I used to self harm. Im going into deep depression and idk what to do. There's so much of me that no one knows. Not a single person knows who I really am. There are times I cry out of no where I could be having such fun time but when I think about my life it doesn't even take a second to brust out a cry , I just wnna sleep all the time, I'm always thinking about suicide. But my BF he's such a sweet guy. He doesn't deserve to be with a girl who doesn't even wish to live. He's always talking about how he wants to get engaged to me at 18. He sees his whole future with me, I would smile at him and say yes baby that will happen but In my mind I say sorry to him millions of time because Ik at some point I won't be here. But idk what to do either I wnna be strong I wnna show every one who's letting me down (mostly my family) that I'm a lot better than they think I'm. I wnna prove them all wrong. Ima strong believer of the saying that pain is temporary but for me this pain been with me for so long that I can't deal with it any moreI wnna make my bf's dream come true. I feel so bad that I'm in a way leading him on. He doesn't deserve this. I'm sorry if this is long but Someone please tell me what to do and how to tell him about me. Our communication is 💯 we talk about anything and everything. I'm just scared as to how he will react because like I said I have never told anybody what I go through. Please help me😞😔