Guy has helped me out tremendously in multiple areas, and gotten me out of some serious jams one of which was sort of an emergency.

However, I am fairly confident he speaks ill of me to other guys in our friends group. I have almost 100% confirmed this, yet I am not sure how to address it or confront him about it.

There have been several of these friends who I have observed behaving differently toward me immediately after interacting with him. I have also seen his behavior toward me change around others, and in one instance I actually heard him saying something disparaging.

He talks about everyone else in the group, and with the exception of a couple he is really tight with regularly says negative things about them. Even the closest friends of his he complains about when he is bothered by something they did.

I know WHY people behave this way, that is no mystery. Insecurity is the driving force behind most gossip and manipulative behavior like this. The question is how would you handle it?