small thing triggered me by surprise

I've come so far and nothing seems to trigger me anymore. But, out of the blue, an innocuous comment sent me in a spin. I've had some suspicion that his new target is a very nice married lady at work. (We all work together.) I worked through the urge to warn her since I don't know anything as a fact. The last couple of days she's complained about being so tired. Now, that could be anything, but I flashed back on all the work days I spent yawning because I'd gotten so little sleep due to meeting his needs. It just flipped on the anxiety switch and I've been on high alert again. I realize it's not that anything she said proves he's using her, it was just my own defense system that went on high alert just from that memory. The good thing is that it hasn't started me back on reminiscing about the good times, and no impulses to unblock anything. It seems I've hit a new level where I almost fear the power he holds to still get in my head. Any advice for dealing with that? I've become accustomed to the peace in my life and I really resent that he was still able to get back in my head. I'm starting to actually hate him now.