Yeah interesting that guy couldnt see your perspective, we should feel sorry for him I suppose. I both agree and disagree with you, wow isnt that so typically me!

I agree we should not keep apologising for our mistakes (they are unavoidable) and life a life free of regret is our goal. I also see that its impossible to avoid regret.
How? I think of it like this, none of us is one single uniform fully cogent person, from moment to moment we are continually changing, due to all kinds of factors. Sometimes we are going to feel empowered and dismiss regret as a waste of our time and value; other times we feel its difficult not to look back and wonder 'what if?'. I do think we can attempt to conciously push ourselves not to have regrets, but denying our true feelings is not healthy.

The only way to overcome a specific incident of regret, is to truly forgive yourself and/or acknowledge the judgement of others; for most people this is difficult. It requires some time out to truly concentrate on the event, how it made us feel, and recognition of its lack of power over us now.
If you feel guilt, in this case you need to forgive yourself.
If you feel shame, in this case you need to acknowledge the judgement of others, then forgive yourself.

So we will feel regret, its unavoidable, but if we take some time out every now and again, we can also deal with the regret, draw a line beneath it, and then allow it to fade into an event like any other.