I'd get a lawyer involved right now. I don't care who left who and how hurt anyone is. Kids deserve to have access to their parents as much as possible.
My oldest daughter played high school volleyball with a girl who actually had 2 cell phones and 2 cars, one given to her by each parent. Her parents hated each other so much that they refused to attend matches if the other one was going to be there. (BTW, her dad was one of the biggest dicks I've ever met.) I thought it was nuts. But no matter how I felt about it, this girl HATED it. She hated completely compartmentalizing her life because of her parents' issues. Her dad was even remarried! WTF? She used to tell my D20, "I wish my parents could just be in the same gym at the same time."
The dad started all of this with the notion that, "as long as you're on my payroll, you won't have anything to do with your mom for the things I provide you". Her mom had to respond because the dad enforced his stupid rule.
Your kids are way too young not to have access to both of you during the week. Oh, and BTW, the courts here in Colorado really frown on alternating weeks - for this very reason. They believe that children need to see both parents during the week. And I have to agree with them. Every person I know who does things this way winds up doing harm to the kids. They are innocent and should not be used as pawns in an adult, dysfunctional relationship.
"There are only 2 ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle."
