My son's girlfriend said to me " I'll F**K you up" ........?

I brought a home and let them and their 2 little girls 2 and 5 ( my granddaughters) move in with me. They pay minumal rent, 325. I have a boyfriend who has been over helping me build a fence to contain my to lab dogs, Bo and Jesse. I don't drink, but brought an 18 pak of beer for my boyfriend to have when we take a break or have lunch. So i check the fridge and the beer was all gone! i told my son that he would have to replace it.......the girlfriend came flying down the hallway and said " why don't you buy up beer" ? Why do you buy Tom beer? I said cuz he is helping me with the fence and he likes it. I just wanted to have some, for when he came over. She was very rude and loud and told her maybe they should all leave for the nite.....she demanded the rent money back and i did go to the ATM and get the 325, she snatched it from me. I even gave them April- May rent for free, cuz of the escrow thing. Now this rent was for May-June and i gave it back to her. I had