I have been with this guy about 7 months now.
We are both fifteen.
He is really sweet,caring,romantic,funny,he's an all around great guy.
Except,he has depression.
He tries not to let it get to him though.
His parents divorced quite a while ago.
He has days where he crashes and gets where nothing can make him happy.
Not even me.
He cut himself once(that I know of)
He said he didn't want to tell me because he knows how it would hurt me
(I have several friends who are/have been suicidal,they all unburden themselves upon me)
He told me though because he thought it was wrong to keep that secret from me.
I reall appreciate his telling me and I want to help him.
He hasn't done it since.
I really care about him and I want to know what to do and how to deal with this.
Please give me some advice...

How about suggesting counseling?

Its not yours to fix... please bear that in mind. I am a wee bit concerned about that because of how you state friends unburden themselves to you. I hope there are other friends in the mix that you can unburden yourself to as well. I am with Krs in that he needs to seek counseling. Depression is not something to trifle with and cutting can grow into an addiction. If he won't get help, you have only two choices: live with it or leave over it.

Its not yours to fix... please bear that in mind. I am a wee bit concerned about that because of how you state friends unburden themselves to you. I hope there are other friends in the mix that you can unburden yourself to as well. I am with Krs in that he needs to seek counseling. Depression is not something to trifle with and cutting can grow into an addiction. If he won't get help, you have only two choices: live with it or leave over it.

Exactly!!

There are many ways to give support - Sometimes just listening is big help. You might find watching a funny movie, or going out and doing some activity, at those times when he is down also helps. When you talk, you might also want to point out all the possibility and potential that exists through a person's life. Looking beyond just the current circumstance gives perspective.

As above, you might also suggest he seek a counselor - Perhaps through school, or his parents.

If you know your friend is suicidal, or is in imminent danger of hurting himself, call 911 immediately and get professional help.

He needs to seek professional help. There are medications available to treat depression and he needs to speak with his doctor immediately. It may take some experimentation to find the proper medication and the proper dosage so time is of the essence. Encourage him to do this without further delay.