(It isn't happening now.)
That is one of the main/key phrases to tell those with PTSD who are being triggered/flashbacking. It takes many, many, many (shall I say MANY?) times of hearing this before it begins to affect the thinking and allow the person to begin to realize that truth. It's the nature of the beast. Try not to feel as though you are being minimized with how you are feeling, but that you are getting good therapeutic responses to how you are feeling.
PTSD makes it so a person stops thinking rationally at times. The reality, as you know, "changes" during those times. It takes logical thoughts and words to help become grounded again, in yes, those are bad feelings but they aren't happening now, you are here now and this is now and everything is really okay right now.
(((((big hugs))))

Trust me, I've been through the worst part of PTSD and can often calm myself when triggered. This hurricane season is tough for me, as the accident happened during a thunderstorm (part of why no one helped me-they didn't want to get wet???) There was a T storm last night that was right over top of my home, the house shuttered each thunderbolt. But though I readied the closet, I didn't go. You can get to where PTSD doesn't run your life.