He ****ed up. And, given how you feel about this, he may very well have broken the thing that makes the therapy work. Because you now never will know when his next 'blowup' will be. And that means that you can never trust him again - not the way you did before.

Basically, he failed to provide the service he is supposed to provide. He failed to honor the fragile relationship and the trust that a client puts in a therapist to be there therapeutically.

And over a silly thing like ten minutes?

Sorry this happened to you. It must be really odd for this to have suddenly happened after two years of being in therapy with him. Have there been other signs of this instability?