Have you ever had your boundaries pushed to the point of a sudden reaction or something similar?

Yes.

It can be a good time to take an immediate "full stop" and assess/evaluate the situation.

Sometimes, it might hit you later, that what happened was way past where you wanted to go and you don't want to return there again. Fine. Tell your partner. Let them know how you feel.

Or if you decide that partner isn't right for you, that's okay, too.

We are all wired differently. Thank heavens!

It may be hard to tell between "sub drop" after a fun session and a "whoa" that was horrible, "I feel like crap about what happened." That's okay, too. Give yourself time.

Communication is clearly important for moving forward.
Communications with yourself, and your partner.