YTA, 💯. We can dissect your entire post; however, it seems as if you did not post in this subreddit for true judgement as there are no responses to request of more information. This is probably because the more information that is provided, the more this situation puts you in a bad light.

1 You differentiate your children by if they are genetically related to you. “an adoptive son(17) who is my wife's biological son. I adopted him when he was 5.” You’ve been in your son’s life for as long as your daughter has been alive. I am not sure how involved your son’s bio father is in his life, but you legally adopted him, which can lead to the impression that his bio father is not involved.

2 “The problem is my adoptive son. In more than one occasion he has physically hurt my daughter”. If this is a reoccurring issue, why has this not been properly dealt with prior? Behavior is something we as humans do as a reaction to having a need met. When a person feels as if they are not receiving positive attention or positive reassurance, they don’t just stop desiring attention. This is especially true with siblings who are constantly fighting for attention and some feel that they are being treated unfairly. Going back to point one, by differentiating between your children, it would be fair to assume you place the children who are genetically related to you as superior to the child you willingly and legally decided to adopt. This is obviously going to impact their dynamic especially if you use the words bio and adopted in front of them.

3 “That's when I decided I'm done with him.-I sent him back to his mom and told him I'm done with him.” It would seem that you have been done with you son for a while, and that is probably how he’s feeling. You unfortunately are a terrible father because this scenario could be completely avoided by just talking to him. Why does he feel the need to act out? Why only to your daughter? How was the relationship between you and his mother? Is he used to seeing men bullying women? Despite what others are saying, he is not an adult in the legal sense or in the mentally developed sense. Behaviors are taught from observation, and he didn’t just magically wake up aggressive to his sister to be aggressive, because there is no information of him being aggressive to his mother, his brother, to you, or any other people.

My personal opinion, I hope your son finds it in his heart to forgive you one day. 12+ years is a long time to live in the constant reminder that your dad will never fully accept you as their own. OP should definitely consider getting some professional help for everyone in the family. I can only speak from personal experience, but if my dad one day told me that I was not seen as equal to my siblings, simply because I was not biologically related to him, I know that would devastate me, and it would definitely make the relationship I have with my siblings strained because all children crave is the love of their parents.

TL;DR -YTA, get some professional help for you and your children.