Nice buck. Sounds like there's a bit of background info that some of us may have missed regarding your grandfather. I can certainly understand your frustration, but, it's a really bad idea saying things like "I wanted to kill him" particularly when your sitting out there with a high powered rifle in your hands... You need to control those emotions and deal with the problem rationally.

If he's no longer the owner of the land, your grandmother can have him cited for trespassing. And, your state may have laws prohibiting interfering with hunters. You can check on that with your game warden. If you've got a cell phone, put the warden's number in your phonebook, and give him a ring next time grandpa is messing with your hunt...