I am sorry with what your going thru with your close friend. You sound like an amazing friend & I'm sure he appreciates you being there. I wish I had some great advice to tell you. I know with my own depression that I feel very guilty that as much love as my husband and 7-kidz and grandson gives me, it just doesn't fix me. Its hard to explain.
Your friend will be in my thoughts and prayers as well as you. Just being there for him and letting him know that you are there if and when he ever wants to talk. Your caring & so supportive and thats something he needs right now.
Your Healingwell Friend,