Someone once asked...
Someone answered with kindness...
Because both people and feelings are more complex than a simple binary of good and bad. The person may have hurt you, they may have hurt you beyond all hope of relationship repair. And yet they still may have possessed some good qualities or been a part of fond memories and there is a natural grief for those parts when faced with moving on from a hurt and a person who hurt us. It doesn’t mean we should return to someone who has hurt us. It only means we still retain the capacity to recognise and grieve the good in them. We can hold both things, with care, and do what is right for our safety and our emotional wellbeing by tending the grief and upholding our boundaries.
Another soul answered...
As I see it, there is a psychological answer to this, and there is a spiritual or existential answer. I will give both, and forgive me if it seems long-winded. On the one hand, relationships can often be unhealthy or co-dependent. We crave that connection and the feelings we received by being part of that relationship, even if we acknowledge that person did a lot to hurt us. In such cases, we don't really miss the person themselves but all the feelings we associated with being in that relationship. On the other hand, in a certain sense everyone hurts people. Your parents, your spouse, your children, can truly love you and want what's best for you. But they are still fallible people, liable to make mistakes and sometimes those mistakes will hurt others. You yourself can likely think of someone you love who you have wounded. Only you can figure out for yourself what sort of relationship you had with this person, the former or the latter, and then, I believe, the answer will be more clear.