Communication can be a challenge no matter the circumstances. It's especially difficult if emotions are running high. If you are recently divorced you most likely have run into problems in this department. The suggestions that I have will not be as helpful if your ex is under the influence of substances, or if they are the reincarnation of Stalin! There are limits for everything...
That being said, the suggestions are simple, but challenging to put into practice.
To begin with, it would be helpful if you created a Persona for this new stage of your life. A Persona is the mask you wear in different settings; you have a "Party Persona", a "Work Persona" etc. Create one that has nothing to do with being a victim. If you have one that feels like it's problem-solving focused and cooperative, use that one. Put on your Cooperative Persona and ... TRY TO COOPERATE! Notice if you had a physical aversion to this idea just now after reading. Take a deep breath if you did, and have faith that things will get better.
Here are a few suggestions on how to go about practicing this. First off, reconnect with the memory of falling in love and marrying this person. That person may not be visible any longer, but surely some qualities are still there. This is why it was so hard for you to leave them in the first place. So take some time and remember the human-being behind the betrayal, or the anger, or the frustration. When you're talking to your ex, try to remember this person. Attempt to leave your grievances and betrayal at the door. Make the effort to remember the likable human-being underneath. Find yourself a good therapist who can help you clear up all of your toxic feelings toward the person so that it will less effect your interactions with him/her.
Prevent yourself from shifting into hostility, arguments, passive-aggressive responses, or bitterness. Stay with the persona of "cooperation". If the other party won't play along, be okay with walking away and letting them know that you will try this again another time. A helpful resource is a book series called "Nonviolent Communication" by Marshall Rosenberg. Reading it can help you become more skillful at communicating.
You once loved this person enough to try for a life together. That part of your life is still worth honoring. If you need to fake the attitude until it comes more naturally, do so. It's the anger and hurt that your ego and heart have suffered that prevents decent, effective communication. Stop operating from your woundedness. Notice I've said nothing about forgiveness here. You can make room for that later.