Ex Relations

How do you get along with an ex who doesn't want to get along with you? Is there a way to get through all of the bitterness they have to co-parent? Personally, I don't think it is possible until the other person is ready to do the same. You can't change other people. So, how do you handle it if it goes on for years - not just 1, 2...5...10 years but longer? Did you find something that worked for you? I feel like after all these years, things are probably going to stay like this indefinitely. The habits are set, the trust completely broken...and we're on the downhill until the kids turn 18. After all, if the ex was going to come around and act human, they likely would've done it in the first decade right?