I used to have so many regrets ! However, I have realised that regrets are just a delusion generated by your ego. It is a consequence of comparing yourself with your expectations and other folks. Its natural to have regrets but its also a delusion. By this I mean that regrets are imaginary, a ghost of the past.
We all have regrets. IMO, the key is to remember that they are a fantasy and as with other negative emotions, to let them go. They only harm.
Hope that helps