Way that I have acted, and I replay them over and over and over again and I ask my self why did I do x instead of y
Discussion
it happened for a reason. maybe it is better that way.
pray and let God take over some of your decisions. He may do a better job.
outsource some thinking to Him.. trust.
According to Buddhism, we usually make "bad" decisions usually because of a mixture of attachment, aversion or confusion. Those are the 3 poisons in Buddhism. The origin of all "bad" or unwholesome decisions.
If you make more wholesome decisions (the reverse of the 3 poisions) you'll feel more relaxed.
I have this problem when falling asleep at night as well... just rehash every conversation I have had(also why I am just antisocial, it's easier)... did use weed to help numb by brain for a long time, but have stopped that. I find the 4-7-8 breathing method for about 5 minutes helps me calm my thoughts and drift off to sleep much quicker. You could try NSDR if you just want to recenter your focus during the day.
Ah, that sounds more like rumination than overthinking. Cool if I DM you a couple more questions so I can point you to some things I've found that helped me?