Bless your co-parent just as they are. Let go of your expectations about co-parenting. Then parent as best you can. Release everyone, even yourself, from the expectations and dreams you had of a wonderful co-parenting relationship.
Two people agree to have kids and a huge shift happens in their lives and their future together. You are committing to a lifetime of connection with this person, even as you are agreeing to bring new dependants onto the planet. It's a massive transition, this becoming a parent. Deciding to divorce your co-parent is another huge shift.