It sounds like it is time to move on. I hope that even though you are moving on, that you can still maintain the cordial relationship for the sake of your child. Plus, it really does make co-parenting easier if you are on a cordial basis with each other. With my XH, we don't socialize together or anything like that, but we do talk about decisions about our children by email and phone, and sometimes in person. We keep the conversation centered on our kids (kind of like a business meeting) and don't stray into personal stuff.

Good luck.