I doubt there's any real way to know.

When you start to talk, you'll know it's time to stop if you just can't keep going? Like... I don't know how you are, but I lock right up and just can't get the right words out - I'll start babbling about something else or going around in circles, or just sorta freeze.

Just tell your T that you aren't sure how much you'll feel like sharing and whatever your plan is - with my friend if I am getting upset I'll just go "we need a new topic!" and that works - those friends do the same to me. But you could always work out with your T what you want the process to be if you get overwhelmed - even go over what you'd be most likely most comfortable with having them do in the case that you freak out or break down crying.

That's about the most prepared you can get.



Good luck!