Just had my first session and almost threw up

My therapist and I agreed that I’d try to keep the advice seeking to a minimum but I have to share my feelings. Right before we started he asked a few questions that I’ve never thought of before and it took me right back to the event, I felt like I was actually there in real time. My SUD lvl was extremely high then decreased as I was just trying to calm down during the first few sets. But then when I started thinking about the event and negative belief during one of the sets, I actually almost threw up and had to stop. I usually get nauseous but not like that usually. I almost just threw up again after thinking about cheating on my wife, which I take to mean that I really don’t want to re-explore the event. I’m a mess today