annoyed

how do you nicely tell a grandparent to back off ? every time I try I know it's going to come out mean and I'm going to be the bad guy. I get that he's the first grand baby but he's still my child and if I say don't pick him up don't pick him up! He's a cry baby because of his papa and his papa has no limit and I'm starting to get to the point I'm just going to snap at him and be a bad person and not care. you know he gets upset when you leave so why walk in my house uninvited and hold him for 10 minutes then leave so I can deal with him having a fit and crying for half an hour before he finally fell asleep and wouldn't ear his lunch... I don't care if he is your grand baby BACK OFF !