It's a hard position to be in.....you want them to be at peace and out of pain yet you don't want to see them go....I know exactly what you mean. Carolina, I think your Dad knew just how much you loved him and wouldn't want you kicking yourself for anything that you did or didn't do. In times like that we do the best we can. After he passed, I disected everything I had done for my Dad and finally came to the conclusion that I was wasting my energy and my Dad would have had a few choice words for me for second guessing myself...
Like Twink said, it was in God's hands all along.
Give yourself some time......you've been through quite a bit and it's physically and mentally exhausting. You've got a bunch of friends here who care very much about you. Please take care of yourself.