Does my ex husband have the right to refuse to meet me halfway with our kids bc our decree doesn't state it?

Our decree states that I have liberal and proper visitation with the kids but he refuses to meet me halfway, or share the cost of transportation, because our decree doesn't state that. It's a 400 miles round trip to get the kids and he wants me either to drive down and pick them up on Friday and bring them home again on Sunday or stay at his house for the weekend. There is obviously a reason we are divorced and I have no desire to spend the weekend at his house. He is remarried (to my sister) and I am engaged but he doesn't want to give up any control as to what the kids do, ever!! Any lawyers out there have any advice? I can't afford our local lawyers!! Thanks for any help!!