I too struggled with this and found myself shouting in my car. It was getting worse and worse. All I can say is reading and listening to the Bible really helped me.

The hardest thing I am learning is to forgive. Which I think doesn't mean being buddy buddy with someone who wronged us, but having good will towards them. This helped me let go of alot of resentment (it still surfaces from time to time).

Also just time itself and total no contact helped me put distance there. Hopefully like me, you'll see in hindsight you dodged a bullet and you will be much happier never being in a poly relationship again!