When I've wanted to talk about a difficult topic, I wrote down a brief description (could be just a couple of words) on a sticky note and folded it in half. I handed it to T when I first got there so I couldn't get out of bringing it up. Also, if you are in a situation where you can email or text your T before your session, you can use that to let him or her know that you have this topic to discuss and you're letting him or her know ahead of time so you can't avoid it. Just a couple of things I've done before that helped me avoid the last minute "blurt."