Wow Michelle, a lot going on here.
Michelle, you bring up your belief in God. Why does God permit suffering? I don't know for sure, but I read The Purpose Driven Life, and the author says the purpose suffering serves is that the suffering let's us know Jesus (as He suffered, we can associate with Him in our suffering)and suffering leads us closer to God.
When I have been in my darkest hours, I have turned to God...interesting that even suffering serves its purpose. It isn't a punishment. It is part of our experience as humans on this earth...but none of that makes it suck any less.
Regarding guilt. Michelle, cancer is a no win situation. Even if someone is cured, it takes its toll. You don't "win" you survive. You could have done 1,000,000 DIFFERENT things, but they may not have been better, they may not have been worse. But did you do everything you did out of LOVE? Then you did 100% the right things.
Michelle, I know you have done a grief counselling meeting. Any chance you can also do a 1 on 1 counselling too?
BTW, to this day I wish I had been more of a force in the ER my mom's final 24 hours. They were a bit of a mess and didn't do everything they could have...I could have been forceful, but wasn't. But I have to let it go. I acted in the situation as best I could at the time knowing what I knew. Guilt will do nothing for me now. It will do nothing for you either.