Sunrise, does this sound like the type of apology you would send:

On the ride home I realized I got a bit angry towards the end of the session. I’m sorry for displacing it on you. I didn’t mean to be disrespectful raising my voice and drop a bunch of f-bombs. I know you are trained to take it, but it doesn’t mean you should have to. Sorry

I fired this email off to my T after my last session. It was a difficult session. I felt like she smacked me around a bit. I held things in check until near the end when we talked about a relationship issue. At that point stuff just started to ooze out of my pores. My anger was not directed at her but I did feel like my voice had raised and I definitely said the f-word a few times.

In hindsight I think the anger inside felt a lot more intense than what actually came out. From my perspective today, sending the above email just made me look like more of an idiot. If I could retract it I would.

Although you may be losing sleep over the interaction, I'm sure he isn't. You might consider holding your apology until your next face-to-face meeting. Then just start the session with, "Hey, last session I felt like I may have been a bit too expressive." "If this was the case, please accept my apology." If in fact you were too expressive, then you've recognized it, apologize and the rupture should be fixed. You both can move on to other matters. If on the other hand, he felt that your expressiveness was in fact a good thing (maybe just needs some refinement), then you've opened the dialog and you both will talk about it. If I had the chance travel back in time, this is how I would handle it now.