Those profoundly physical reactions are frightening, but your T's quick attunement to what was happening was awesome. That time spent calming and breathing is actually invaluable. What you experienced is that there are means by which you can regain control and safety for yourself and within yourself. Yes, your T guided you through that, and in time you may find you start internalizing some of that ability on your own. You have an amazing therapist, and you are making growth through very difficult issues.