My friend killed himself, I learned he was lying to me.?

If he was messed up enough to kill himself... well, then it doesn't surprise me that he lied to you. The reality is you don't know what was going on in his and never will. You'll have to give him the benefit of doubt on this one, because there's no way to talk to him about it. I think it'd be easier on you if you just let it go and thought of him as the great friend he hopefully was... A few white lies shouldn't change anything. And remember, he was feeling more than you might be able to imagine...