It is absolutely not insensitive or hurtful to others for you to disown your abuser. You are absolutely in the right to do this, and many children of toxic parents do the same thing. You can call him sperm donor, or call him abuser, or any other word that you think fits the terrible things that he did to you. 

I am so proud of you for being able to get away and distance yourself from someone who was so hurtful to you.