Can the court compel ex-husband to change visitation schedule to appear at child's sporting events

Sporting events interfering with visitation: I am divorced and have sole custody. My ex has visitation every other weekend from Friday night to Sunday night. He has visitation for half of the summer, one week at Christmas and spring break every other year. My son tried out for the junior high basketball team but did not make it. He really wanted to play basketball, so I signed him up on a local sports program. The team will practice twice a week and have a game every Saturday morning (8 to 9 am) for eight weeks. I told my ex about this and said that I wouldn't be able to bring the kids to him until Saturday late morning. We meet half way and he lives about 4 hours away. He said that he would not agree to this as it interferes with his time. Then he said he might do it if I agree to add on extra days during the summer. I talked with my son and he said that he did not want to spend extra days with his father. (His father is, at times, verbally and emotionally abusive to our children.) My son does not want to miss his games either, though. My ex will never agree to a compromise. What can I do? I do not want to get into a long and expensive court battle with him, but at the same time, I don't want my children to not be able to participate in their activities.