In a video which I highly recommend, The Frank Friar talks about regrets:

I really like how he distinguishes a proper resolve to make amends where making amends is possible and an inordinate attachment to the past where action in the present isn’t possible.

Much of life is reducible to: do what you can and trust God for the rest. But it can be very beneficial to see the specifics of that in each circumstance because that sort of fundamental orientation is hard, in this fallen world, to achieve.