I worked through triggers by making it clear to myself in that moment that the stuff that is getting triggered up is from the past and that this is seperate from the situation that I'm in at that moment. I also did a lot of analyzing afterwards to make a better plan for the next time. After a half dozen or so times the trigger was extinguished (it got less and less every time). It would help for you to discuss the stuff from the past that is getting triggered up in session also.

When you are in therapy can you tell your T "I just got triggered" and then you can go on to explain what happened and discuss the whole thing?