I hate the case where it looks like you'll be able to go through the metal detector then you're redirected. Happens all too often.
Sympathize with the OP and understand how her backstory makes her perhaps more sensitive than other pax; she might have gotten a better outcome if she had disengaged, left, and flown later that day or from another checkpoint if available. Not sure the specifics of IAD since I avoid that place like the plague.