Dealing with Guilt After Discovering Father's Sexual Abuse

TW/ sexual abuse . . . . So, it’s been nearly a year since I found out my father was a pedophile and molesting and raping my sisters and cousins and this month has been really rough on me because of the year mark coming very quickly. Anyways, I feel really guilty about all of this stuff when I know I have no reason to be. I feel awful that I’m his flesh and blood and I can’t look at my sisters without feeling guilty. There are times I wonder why he didn’t do that stuff to me instead, and I feel bad that he did it to my sisters instead of me. I know that I shouldn’t be guilty for being his blood and that I can’t change the past or influence him to stop it to go for me instead. I know that I shouldn’t rationally think this way, but that’s all I feel. How do y’all deal with irrational thoughts of guilt like this? I’ve never really struggled with guilt until the past month or so and I’ve never experienced it in my older traumas either. Any advice or help is much much welcomed!