Was I fair in how I resolved this messy situation between me, my good male friend, and his wife?

I think you did the best that you could in that situation. I don't know what else to say about it. Your friend's behavior was very disturbing in not just blaming you but in not seeing how unwell his wife had become. Maybe he was having problems coping with his wife's depression and needed someone to blame or help and that's where you came in. That wasn't a fair situation to be put in, so I can't even say if any particular action would have been "right."