I have and I haven't.
I've forgiven my mother because while in therapy I've learned that she has her own illnesses and really did the best she could do and then some.
I forgave my father and was blessed to have almost a year with him before he passed. Prior to that I'd not seen him for 14-15 years...his choice. I didn't know where he was.
My older brother and main abuser? No. I think I could if he was a halfway decent person today, ya know? I would like to think he was just a messed up kid trying to make it like we all were, but I can't. He's still an ugly, dangerous person who's been accused as an adult.
To answer your question, it is possible. It is difficult.
I wish us all well with this.
KD