The only way you can be sure you haven't killed anyone with HIV (assuming you are positive) is to test every one of your sexual contacts over the course of their life. If they get sick or die, then it is still possible, with the best of current technology, to determine if they died from a strain of the virus they got from you. So, unless you've done this level and intensity of testing, then you can't say for certain if anyone has died or gotten sick after having sex with you.
What probably happens, in reality, is that uninfected people have sex with a number of infected people and get the virus from one or more of them. So it then becomes possible for any one HIV+ person to say, with some belief, that they did not pass HIV on to a given person--so responsibility is lost in the crowd. There is the possibility for each infected person to say some other person didn't get the virus from them. This is nature's way of saying that having sex is more important than being responsible.
Unless a complete fix is found for HIV, then you can look forward to the epidemic continuing largely unabated.