The First Step is the Doozy
Once you have that first light, bright and short conversation with your Ex the next encounters must become easier. You’ve already proven you can hold a conversation without bloodshed. The next meetings are as light and bright and maybe a little bit longer.
You talk about what you want.
Don’t let your EX control the conversation or make it serious.
No matter what.
Many EXs can’t deal with the fact you are no longer insanely in love. That the power s/he had to hurt you is gone. That you can bubble with your Ex the same way with a waiter, a salesman, a clerk, because in your life, your Ex is no more, and possibly less important than those people who have use.
If you let your Ex make you angry, or cry, you should go on a diet of tepid water and stale bread for the next two days. And then, you will start again.