I think a letter would be a good first step. With a letter you can take your time and be sure to include all that you want to say, the way you want to say it.

Then, when the letter is ready, you could arrange a phone call and then email the letter shortly before the call.

On the call, keep to the text of the letter and don’t waver in response to what he says. If you feel yourself wavering, one possible technique would be to say that you wrote down what he said and you will think about it and email him in two days.

Think of the airline expense as a form of therapy! You are learning a lot about yourself. Or maybe you could get a credit and use the money to take a trip for you.