Originally Posted by
Ariesagain 
A big part of what you’re experiencing is no doubt biochemical. She blindsided you and your body dumped a huge jolt of adrenaline and cortisol into your bloodstream.
Then all the dormant neuroreceptors that associate her voice with both pleasure and pain woke up.
So you basically have a toxin exposure hangover and the byproduct of most hangovers is anxiety and regret.
Be gentle with yourself. Eat well, lots of water, exercise outside if you can. You should be feeling grounded again soon.
Totally this ^^^^
Reactions to shocks like what you describe are physiological as well as psychological. Your sympathetic nervous system registers contact from your ex as a fight-or-flight situation because it (perhaps unlike your conscious mind) perceives this as danger. The sympathetic nervous system can’t tell the difference between a physical threat (sabre-toothed tiger jumps out of the bushes) and a psychological one (someone with whom you have a long attachment history is trying to get you back in their net).
So a ton of catecholamines, including adrenaline, are dumped from your adrenal glands into the rest of your body prepping you to run or fight for your life. This cascade can leave you feeling shaky, sweaty, nauseated, hyperaware etc for a long time, long after your brain has processed the fact that you aren’t physically in danger and stood down red alert.
For me, understanding the interaction between sympathetic and parasympathetic nervous system and how they respond to cues from the external environment was huge, and helped me understand that I wasn’t crazy when dealing with my ex made me feel physically sick - I just had lots of chemicals and electricity running around inside me.