The parent is always in a more powerful position psychologically even when you are no longer a child. That power imbalance never goes away no matter how old you are. The parent may no longer be literally in a position of authority, but emotionally he/she is always perceived that way. That's why the entire responsibility for keeping the boundary of the relationship intact lies squarely on the parent, never on the child, even when the child is an adult.

From a legal perspective, incestous sexual activity has various degrees of prohibition and punishment in many states, the severity of which depends on a particular jurisdiction. Unfortunately, those laws seem to hold both parties equally responsible, which is purely medieval IMO and reflects that our collective consciousness is still on the level of the dark ages.

However, if there is evidence of child sexual abuse that continues into adulthood, I assume, only a perpetrator is held legally responsible, but, with some of the crazy laws in some states I wouldn't be surprised if that's not the case.

So, from the legal standpoint, your situation may be quite complicated. From a psychological perspective, to me it's absolutely black and white in terms of who is responsible for what's going on, and that is definitely not you. In terms of the emotional dynamic of your relationship with your father it is also quite complicated, not black and white at all.

That's why a part of me feels for your therapist, because this is not an easy case to deal with. Still, I would approach it differently. But then, I also have to consider that I am not there and I don't have the same opportunity to talk to you in detail as she does.