My friend has a crush on me, but I don't like him

My friend is getting really depressed because he likes me, but I don't like him that way. He hasn't admit it to my face, but he's written it and I have irrefutable proof that it was him. I don't want to date him on false pretenses, because that would hurt him more than if I told him no one would ever love him. We are good friends, and I don't want to ruin that.

I'm sorry, but the only solution I see is to tell him how you feel. That friendship may or may not be ruined by these choices(most likely it won't)