Hi! OP here. I promise to not bump this thread every time I dive, but I did want to give one update since sometimes I wish people had come back with an update when I search for old threads like this. We did another dive today and it went great with no prolonged anxiety and no need to surface! The primary changes we made were to:
(1) talk through a dive plan beforehand,
(2) come up with a specific signal for "I'm having anxiety" and hold hands for a minute or so while just breathing (I noticed during our OW cert when our instructor held onto my arm firmly during an exercise that my buddy having a grip on me calms any rising panic, for whatever reason)
(3) take a breather after unloading gear and not rush so much,
(4) take a minute after the initial descent and just get adjusted instead of immediately taking off.
I only had to use the "I'm having anxiety" signal once and it was shortly after the initial descent; we had problems tying off the dive buoy due to strong current, and viz was only about 5 feet for the entire dive. Being able to give a signal that "I'm physically okay but my heart is racing" was great because my husband just grabbed my hand, made eye contact, we took a few deep breaths together, and I was good to go. We also learned that we need an additional signal for, "That SOB jellyfish stung me and it f-ing hurts" (heh) and, on a more serious note, a signal that one of us is going to check the other one's tank. Towards the end of the dive my husband was behind me and noticed my tank was slipping, so he grabbed me by the tank to tighten it ... but I thought I was caught on something since I couldn't feel that he had grabbed me. I tried to twist and the more I twisted, the firmer he held me in place by my tank. (When we talked about it later he said, "Yeah, I just thought you were spinning around for some weird reason" and we laughed, but I let him know - I'm pretty much never going to wildly spin around under water just for kicks, lol.) In all the confusion with my arms flailing to try to see if my alternate was caught on something, I accidentally ripped my own reg out of my mouth.

Thankfully that was a wake up call for me at that moment to calm down and STOP FLAILING, and I was able to calmly replace it without issue. By that time my husband had fixed my tank and I figured out that I wasn't actually caught on anything, but that little learning lesson resulted in us coming up with another signal for "I'm going to check your tank, turn around".
Thanks to everyone who gave suggestions and, most importantly, encouragement. I built a lot of my lost confidence back today and we had fun despite the bad visibility and numerous jellyfish stings. We can't wait to dive again next weekend and now we understand that some dives may suck and that's normal, but the good dives make it worth it.
