Has a health care proxy ever questioned their decision for end of life care decision on behalf of their parent's wishes?

On May 1st my mother, who had COPD fell and broke her hip. The decision to operate was made both by my mother and me. My mother was unaware that she would have to be placed on a ventilator with a breathing tube after surgery. I knew, but without agreeing to post surgical procedures they would not have performed the surgery and she would have become bedbound, in excruciating pain in a nursing home. I knew my mother's wishes about end of life decisions and how she would want to live plus I had her healthcare proxy directive that stated such. I only allowed the surgery to go foward because I could not have my mother suffer in the pain of having an unrepaired hip fracture. Unfortunately, they could not wean my mother off the ventilator due to her end stage COPD. The living outcome would be that my mother would live off a ventilator with a Tracheostomy tube in a nursing home. I knew my mother would not want this. I had to make the difficult decision on her behalf, to remove the breathing tube hooked up to the ventilator and let nature take it's course. She died two hours later peacefully with family around her. She died May 10th of 2014. It has been a month and a half since she past and I am still questioning if I made the right choice. She could still be alive today if I had chosed differently, but with significant decline in her quality of life and what she would want. I cannot get past the idea that I held her living or dying in my hands. I know this is want she would want in my head, but my heart feels elsewise. How do you come to acceptence on the decision you made to end someone's life that is what they wanted, but unsure in your own heart?