Is it normal to limit my parents involvement in my children's life

I have never had a good relationship with my parents. My father was very abusive (physically, psychologically, verbally and emotionally) mother and me when I was growing up. My mother didn't abuse me but she didn't do anything to protect me either. I guess you could say that my father has mellowed over the years (I am 40 now),but we have never really gotten along. My mother lives in her own world and lets my father control her every move. The fact that I would not and will not let him control my life has led to a lot of issues.

Four years ago had beautiful boy/girl twins. At first my father was supportive and I felt that he had turned over a new leaf. He seemed to really love them and want to be around them. My mother was very pleased to finally have grand kids. They were very helpful with monetary things and took the kids often as I was going to school at that time and am a single parent. I was fine with this because things seemed to going well, and they seem to really like having them. However as my kids grew I began to notice things that concerned me. When they were two I began to feel like my father was using my kids as a way to gain some control over our lives. He would want the kids at a moment notice,and he would bring them home early w/o calling. Things like that began to bother me, but not enough to stop letting them go over to their house. Then about six months ago more things started to concern me. My kids started telling me that papa's (their word for grandpa) is mean. They would never tell me why he was mean and to be fair they sometimes say that I'm mean too. But was enough based on my childhood to make me wonder what was up at their house. Also I began to notice behavioral problems with my son. He began name calling, he called his sister a stupid brat. We don't call names in our house so I wondered where he learned that. To by fair he could have learned it at preschool, but I instantly thought of my father. Still even with all that I still let them take the kids once a week sometimes overnight.

Then about 3 weeks ago my mother calls to ask if they can have the kids after saying that they weren't taking them. I said my son was coughing and she said that she would ask my father and let me know. An hour goes by and no call and it was lunch time (2.00 pm yes we eat late) so, I called her to see if they are coming or not. She says they are but not for another hour or so.I'm was not happy about that but still said okay thinking they would keep them overnight because of the late pick up time. Then she says that my father doesn't know if they are keeping them overnight or not and she will let me know. Well that didn't cut for me and for the first time ever I said so. I told her to either take them overnight or to take them on a different day. It was getting late and I didn't want disrupt the kid’s day and schedule for a few hours. Well this led to big blow with my father. He said I didn't have the right to dictate policy in their home, I said when it comes to my kids I have every right too. He started saying that because all the thing they do for me and my kids that gives he the right to do what he wants (they do help out with things like school clothes, bikes etc.) I told him that they still my kids so I DO have a say in all matters concerning them. He then called me an ungrateful b*t*h and said that I could keep my f**king brats then. I responded with fine I will.

Well for me that ended all unsupervised contract with my kids. I will not let him talk to or about them like that. I told my mother that but also told her that she can come see them at our house and that she can take them any place she wants except to her house. Well, she thinks I'm blowing this way out of per-potion and has again sided with my father. She hasn't called or been to see the kids since the blow out even after I explained all of my other issues. She thinks I'm being petty, I think I'm just trying to protect my kids. What do you think?