Yes, I can quite agree with an "as needed" approach to addressing one's regrets and then moving on and counting blessings and so forth. Goodness knows, I could look back on almost six decades of woulda, coulda, shoulda and bad luck and all kinds of regrets about what could have been to the point of dweling endlessly in that bottomless pit. Instead, I choose to say "spilt milk" and "lessons learned", look at what I am proud of and look forward to all the good that I can still accomplish as well as the joy life still holds in store for me.
Sometimes spending a bit of time on the pity potty can help flush away a lot of negatives. Sometimes maybe even a good ol' crying and feeling sorry jag that lasts a long time. So long as such things are "sometimes" and not a regular routine and so long as you DO move on. In the end, I see a purpose in life. So, if I am alive, there must be a purpose. Discovering what that is and how to best accomplish it - now there is a life's work for you!