I’ll give you an interpretation. To love means to will someone’s good and act for someone’s good if possible. This means that it is not only permissible, but obligatory, to do things that might be painful or unpleasant to others, if it is for their own good. I would also say that we have an obligation to love and respect ourselves as human beings. So self defense is not only a natural right, it is a moral obligation. That is why pacifism is heretical and immoral. So, if my killing an assailant in self defense is good for myself and for the assailant, then it is a good thing to do. Now how can killing an assailant in self defense be good for the assailant? Well, there are at least two goods that are achieved here.
First, there is the objective good of protecting my own life. But second, there is the objective good of preventing the assailant from committing an even worse crime, murder, instead of attempted murder. Also, if the killing of the assailant is seen as an act of justice, then the assailant, to some extent, expiates his crime. It is a painful truth but one that needs to be said. Sometimes true love demands that we kill others. Self defense, capital punishment, and killing in just war, when just, are acts of love. We could even argue that killing a wicked person could be both a corporeal and spiritual work of mercy.