The hardest chapter so far

I have been working on my book steadily and just completed what was the most difficult chapter thus far.  It's about my parents' role in my illness.  I don't want to give away too much but suffice it to say that they essentially abandoned me two years before my surgery.  I need to back and add more to it but to tell you the truth, I am dreading it.  I got my mother's current email address from my brother recently but have done nothing with it.  Should I just warn her that I am writing this memoir and she and my father don't come off looking well, to say the least.  Or do I want to re-establish a relationship with her?  I speak mostly of my mother because I don't think my father wipes his ass without her permission.  I want to talk to my brother more about this before I email her but when I sat down with my sister-in-law (who is more like a sister) she told me that if I do decide to try to re-establish a relationship with her I will probably, at the very least, be disappointed by her sometime in the future. But her true feelings are that my parents are not worth it, that their behaviour was disgusting. And this comes from a woman who never stays angry with anyone. Ever.  The fact remains that scarcely a day goes by that I don't think about my mother.  The fact that I am sad that we don't have a relationship and that she wasn't there to see my kids grow up.  I also have a few choice words for her that have nothing to do with me but reiterate her character.  Do I include that as well?  Right now I just don't know.