Responsibility for our Actions

About a year ago, one of the students sent me this question:

"We are instructed to forget the bad done to us by others - the idea being that this was something we had coming to us (karma, taking responsibility for our past actions). My question is, what about the reverse? One could argue if we do bad to others, that we should forget that because it was something that they had coming to them, which, of course, does not sound right. I am wondering your thoughts on that."

And this is what I wrote in reply:

        Good questions. In any discussion on karma, we need to remember that there are two poles: the “doer of action” and the “receiver of action.”
        When someone does something bad to me, that person is the “doer” and I am the “receiver.” As a “doer” that person has to reap the painful consequences of his/ her bad action. As a “receiver” I can (1) blame the person and become bitter about it (which really adversely affects me, not the other person) or (2) recognize that my karma entailed that suffering and, instead of blaming, I bear it cheerfully or stoically, and if there is a lesson to be learnt through that, I make an effort to learn from it.
        Why should I think that my karma entailed that suffering? Because the “doer” could have done it to anyone else, why was it to me and not to someone else? We can either say it was bad luck (which, in other words, means that there is no explanation) or my bad karma (which at least fulfills the law that good begets good, bad begets bad).
        Now, when I do something bad to a person, I am the “doer” and that person is the “receiver.” As a “doer” I have to reap the painful consequences of my bad action. As a “receiver” that person can (1) blame me and become bitter (which does not really affect me) or (2) recognize that his/her karma entailed that suffering…. and so on.
        The world of karma is thus a world filled with “doers” and “receivers.” The “doer” in every case is responsible for his/her action and has to reap the results (joy and happiness, or pain and suffering) depending on whether the action was good or bad. The “receiver” in every case can either (1) indulge in the blaming game and become bitter, frustrated or egoistic, or (2) be grateful for the good received and thank the “doer”, and be self-introspective for the bad received and “forgetful” of blaming the “doer” for it.
        So in none of the cases is there any abdicating of the responsibility of one’s actions (as “doer”) and multiple choices of how to deal with things that happen to us (as “receivers”). Also, I don't mean to suggest that we should passively allow other people to harm us or inflict pain upon us. The scenarios I describe above relate to occasions when we have done (whenever possible) everything we could to avoid being hurt in any way--but become victims nonetheless.