So I went to my partners mums house for Christmas yesterday (who didn't formally invite us may I add). She never wants to see DD so my partner is always forcing her on my DD. I don't like the way she interacts with DD, she claps her hands really loud to get her attention and will shout here and there and expects her to be behaving 'normal'. She hits her bum when she wants her attention and basically treats her like a dog. Anyway, my partners brother got a toy and lightly tapped her bum when my daughter was having a tantrum (she was very tired and throws herself on the floor). I said to my partner that she needs a nap, he then threw a strop because he wanted the little time they spend together to be fun. I don't even know what to make of him and his family, it's all very odd to me because I have a big loving family. My partner came to mine after and got the hump with my 5 year old niece because she kept coming in and out the room with her toys. He whispered 'for fuck sake' under his breath so I told him to leave. The more he does this it really puts me off of him and I consider splitting but then it worries me him having my daughter on his own. What would you do?