This happens to me all the time! I cope by reminding myself that whether or not someone is thinking about our interaction it does not affect or change anything in my present. My worry about the interaction has no real affect other than bothering me. So I release it (or at least try to) because ultimately thinking about it has no point. Hope that made sense!

I really struggled with this to the point of having panic attacks from the thoughts alone. I have found a coping mechanism that works for me, which is listening to music while using a color by number app before going to sleep, or watching a video that will have my full attention (something calm, chill and low key) but won't keep me awake

Exact same with me. You aren't alone at all