I do believe in healing. If it is God's will he will be healed. But, of course, I agree with MrWonder--he needs salvation more than anything else.
I have had my share of run-ins with WoF in my own circles....I once got a very bad flu-like illness at a four day teen retreat I was helping with. The room spun, I couldn't keep anything down, and I basically crawled along the hallway wall back and forth to the bathroom to throw up for the duration of the retreat. I had some well-intentioned folks praying for me and telling me I just needed to get up and walk, and claim my healing. If I had had the strength I think I would have punched at least one of them. So, I forever went down in history as the one lacking faith. LOL Whatever!
If the pressure of dealing with these folks is too much for you, then maybe it would be wise to step back and take a breather. I will be in prayer for you and your friend.