I live in Iowa. This past weekend was my weekend for my children however, my exhusband needed them for a birthday party. I agreed he could have then but they had to be back at a certain time as I had plans for the children. He was not on time with them. We got into a big argument and told me he was going for 50-50 custody of the children. I have had the children full time (except every other Saturday night and Sunday) for the last 4.5 years. He and his girlfriend can't have children and she really wants kids. I cried all weekend. I feel so sick. He told me he is tired of me making a big deal about seeing the kids extra times. I do let him see the kids extra, I just get upset when he doesn't return them on time. Can he just switch this?