JustMary, reading your post brought tears to my eyes
I'm so sorry for your loss.
Reading from your post, I think you did everything you could for your son. It's always hard looking back because there are things you wish you did, or changed, please don't feel guilty though. I think focusing on your health is something your son would have also want you to do too. I hope you have support to make it through this difficult time, also know you have a community here with people who will support you.
5/18/13--->40-34-42 (170lbs)---then the holidays happened
Lowest recorded weight as an adult -->160!