Focusing on the good rather than the bad might make life easier. Ask yourself:
What did I used to like about this person, and how are they a great parent? When we were together, we worked to each other’s strengths. Can we do that again?
What if I was willing to acknowledge, and even compliment things the other parent does really well? For example; “Jack told me how you helped him with his homework. He enjoyed it, thanks.” This sort of positivity can only help each other which in turn will help your children.