My Dad Is mad at me because I don't like his other kids?

My title may sound harsh but I really cannot stand my fathers older kids who are in their early to mid 30's and they treated my mother like crap until the day she died. The day after she died they kept pushing their mother and our father together and it seemed to work unfortunately because they are back together after 30 years being spilt up. It's quite pathetic to see two grown women act like children. For years they have done some very spiteful things to me, my mother and my little sister who is 17. When I got pregnant last year they made a Facebook group page listing the Possible candidates of my baby which was totally inappropriate and uncalled for. My Dad gets pissed because I don't consider them my sisters. When I was 12 I remember when my oldest sister who was 25 at the time pushed me in the pool knowing that I couldn't swim and I almost drowned. I'm just tired of their shyt. Should I feel guilty about not liking them? I'm 21 years old and I don't have time for stress in my life. At 30 and 34 they should start acting like grown women and not children. I show their mom respect even though their mom is a who has been trying to destroy my parents marriage for years. Me and my little sister want to talk to our dad about them, so how can we get him to listen to us? Thanks friends!