You can regret your actions but still accept them. Part of moving forward is accepting that you cannot change the past. You can, however, go some way towards making amends by owning up to your mistakes and that means facing the people you may have hurt along the way. Sometimes that's not possible because the people concerned are not contactable and the best you can do is accept that you did the wrong thing, that you regret having done it but you have learnt from the experience and can now let it go. It helps nobody if you are debilitated by the past. We are all a work in progress and sometimes things get a bit messy along the way. Carrying the lessons rather than the regret lightens the load and helps you to face whatever else comes your way.
I'm not suggesting this is an easy thing to do. Meditation works for me, counselling for others, the Camino for most of us.