Certainly not trying to be "holier than thou," but I regret nothing. All of my experiences make who I am today. Wether or not you find me a good person or not, regardless, I am unique, as are my experiences.
So regret I find to be a waste or energy. Regret is a way of telling myself that I don't approve of who I am now. I'd rather move forward than reminisce about what I should have done.