Lifeskill to change habits

Since yesterday, I have started attending sessions based on Stephen Covey's book of "7 habits". Towards the end of the first session of PARADIGM, the well-prepared faculty Mr. Atul Gore answered my query very aggressively. It was turning into a debate which I didn't continue, but that gave me an opportunity to reflect on my personal strategy of personal relationships. 7 habits & bringing the change in your habits is a ball game to bring success in your relationships in people & thereby bringing success in your life, personal, professional etc.etc.
I had asked him about the essence of the sesson he advocated, INSIDE-OUT. Why it is necessary ? Why to wash out our dirty lining in public when we tend to forget? to which he answered that we tend to carry the past, the horrible past, in present & thus marring our future, to which I agreed but said that I believe that 'forget & forgive' is the best approach to get past of past & I am successful withit, to which he reacted very sharply. I nodded to all what he said but i have a different opinion about it. May be it is my success formula on which I operate & I love those principles on which my interactions are based.
My first principle is 'nobody is bad at heart'. All people are nice hearted, good-intentioned people. Whenever the other person does something wrong, he is correct with his thinking, so I don't get hurt by his wrong. I only think his perspective differs from mine & continue behaving good with him. With my good behaviour, he/she never hurts me thenafter. And I am yet to find bad behaviour people.
Secondly, as Atul gore mentioned, I hold myself responsible for whatever wrong happens with my connections. e.g. I always think we would have been successfull in our social commitments had I been more active. My child would have been more smart had I given more quality time. etc.etc.
Thirdly, this 'forget & forgive'