It's not that your feelings are wrong. No feelings are wrong or incorrect. But recognizing how you feel then changing it is the goal. If you repress your feelings, you won't know what they are and you then can't change them. By letting them come out and recognizing them, you can see which are healthy and which ones are not.
You are going on what you are feeling, which is different than what you think. You know that what those guys did was about them. And you know that you are who you are regardless of what happened. But your feelings tell you differently. So you have two sides to the same coin. It is up to you to decide which one you go with. If you feel it is ok with you to accept that you had no value and that you were simply there for them, you can. But what value does that have for you? If you continue to believe that, what purpose does it serve? It is not the truth, so it's not about reality. It serves some value to you, then. What would it be?
You do care that those two hours mean so much to you. You care because you are a decent person who has the capacity to hurt, care for others, love and feel compassion. And the fact that they tried to take that away from you and selfishly take it for themselves is painful. That is ok. Putting the blame where it belongs is what is important. They did this, not you. Who they are may have been in your life for a while, but it does not automatically become you. It stays about them. You stay who you are.
You may have felt good about yourself before the attack, and that is good. But your childhood did affect you. You had to create who you felt you were out of what you went through. For one, you point out that maybe you had little value before these guys came into your life. Where did that come from? The idea had to come from somewhere. That is important. You may have felt so good about yourself because you had to. You had to create your own self esteem. Add to that the fact that you were young and most people at that age feel invincible and on top of the world. The attack took you down from that. But again, that is about who they were.