My psychologist, who is 60 years old told me that this isn't that uncommon and he has dealt with incest a few times. My eyes are now wide opened and me not addressing the first act was the reason it escalated into what happened. Somehow he related it to my dad being an alcoholic and us sweeping his acts under the carpet. It made sense. I believe the relationship can be repaired. I should have stopped it an called the police. I'm guilty in this also. I am going to follow the advice and stay in treatment for a while. My son saw the same psychologist and I don't know how that turned out yet.
So now you shift blame to your father? If anything, if your father did things which were untoward then you already knew better from past experience. At age 42 you can't blame Dad, and at age 24 your son can't blame you or his father. You are adults, act like it!
If there is any way to have different therapists, then do so. It is not, I feel, the best thing to be sharing the same therapist unless you are doing it as a pair, both meeting at the same time, with the therapist helping you to hash it out. Get a different primary therapist from your son, and as to how his therapy proceeds, it's none of your business.
You are to keep the focus on yourself, you are to focus on moving forward, getting tested for disease and pregnancy.
If you have acquired an s.t.d. or are now pregnant, then you need to talk with the son so he can get medical help and you can both determine whether or not to keep the baby. (Not trying to bring you down, but these things are possibilities)
Once more, if any of this is real, you need to move forward. Incest happens, rape happens, both together happen, what you do with that is your choice. Don't blame others, you became part of it. The only blame will be on you if you don't do something, including reporting the incident to the police...although it's too late for DNA from the scene. If he did this once, he could do it again to you or another woman, maybe he already has a history of this sort.
Odd that you managed all that much self examination in just one therapy session, and not sure why you feel it needed to tell us the therapists age. Once again, your veracity is made questionable.