I haven't read the book, but I do have a couple of thoughts about what you have written.
If you feel like pushing the book away, that doesn't neessarily mean you should do the opposite. In fact it might be important to listen to your feelings. Perhaps at this time the emerging feelings are simply too overwhelming for you to cope with? That's okay, and you can always return to these thoughts later, or in the relative safety of the therapy hour.
Also I feel like there is more room for grey areas in your thinking. It is shocking to think that someone you previously thought of as "good" could suddenly be painted in a different light, but it doesn't have to be either/or. If you feel your mother did things wrong (or even abusive) as a parent, that doesn't have to take away from the positive experiences you seem to be saying you have of her parenting. This new realisation doesn't mean she has to go from being totally "good" to totally "bad". Don't deny yourself the positive experiences too.
I wish you healing.