In some twisted way, my ex-wife assumed that she was the better parent and thus more entitled to the child support, the house, and the kids' care and feeding. As a good dad, this was just her assumption. Today, her assumption wound probably be supported by state family law. But, I believe times are changing.
It was not fair what happened, and in many ways, my ex-wife was the architect and builder of the divorce.
Love your kids with everything you've got. Let go of your ex, as best you can, and focus on the impact your love is having on your kids. Stay true to that value and you will always choose the high road.
My ex knew I would not sue her for 50/50 custody. She didn't want to lose 50% of the time with her kids. 30% sounded almost palatable. Painful, but well worth the freedom she imagined just ahead, as she headed towards becoming a single mom.