I was diagnosed with PC at 49 years old.
All I can remember about the discussion with the doctor was "you have cancer . . . it still encapsulated in the prostate, is very virulent (because of my age) and thus needs immediate treatment, and that treatment should be surgery." Question regarding our sex life afterwards were answered with "I have to save your life first and we'll deal with the ED later."
My doctor was, by nature of his profession, quite pragmatic and narrowly focused on saving my life . . . "I'ts a good thing"
He knew what he need to do for the immediate future but I had no idea what the near and distant future held for me and my wife.
Blessed with 4 kids at the time, additonal progeny weren't an issue. However, regaining a normal sex life presented significant challenges that were never really met and resolved.
With regard to your concern for children, would it be possible to collect and store sperm before the surgery?
If I had to face the situation all over again, and knowing what I know today re long term effects of surgery, I would be very careful to evaluate all other alternatives to surgery so that I could make a more informed decision, Overwhelmed with emotion at the time, I accepted the doctor's recommendations as absolutes.