I think metalman is right on spot here. It's your ex doing this. Unfortunately you don't have much options. You may threathen to cut the money but that could mean you won't see your son ever again. You may go to court (not really sure but she probably doesn't have the right to do this). Or you may just have to put up with it and be a nice 'uncle'. Hopefully, about in 10-15 years your son will figure out what's going on and will hate his mother for doing this. That I know for sure. (unless you do something stupid to piss your son off)
