Who's to blame?

Something I haven't managed to share with anybody I know is the guilt and certainty with which I firmly believe I'm responsible for her death. When I mentioned it to my husband, he assured me it wasn't so. When I mentioned it to one of the ladies at church, she told me to get past that and said "Don't you start feeling sorry for yourself." Which is sound advice, but I don't need to hear that. I don't feel sorry for myself... I feel sorry for everyone else who's been impacted. Yes, I am sad about the loss, and I wish more than anything that I could reverse time and do things different, but I also know I'll be okay. Anyway... back to this being my fault...
She wanted to take care of me that day after my knee surgery... and I told her no, I didn't need her to. Of all the things I could have said... that hurt her. I know it did. I went so far as to try and persuade her not to come. How could I do that to her? She was happy taking care of people. It's what she did. After the surgery, they came over to our house. I wanted them to stay, but didn't want to make them feel ackward or like they "had" to stay, so I encouraged them to go. After they left, I had this VERY strong urge that I needed to pray, and pray hard, and pray NOW. What did I do? "God, thank you for my grandparents. I love them." And popped in a couple Lortabs and went to sleep. So much that I ignored. If I had asked for one last hug... shared one last story... prayed for safety, and kept at it till I had peace... shut up about the eagles so they didn't go see them... talked more about the eagles so they spent just another two minutes watching... asked them to do something for me (anything)... convinced them to stay home. I don't hate myself, but I surely don't like this. I don't like thinking I killed her - the woman I loved more than I can say.