My condolences on the loss of your father. I too lost my father on March 28 so I know exactly what you're going through. The time since then has seemed surreal, especially going through the summer without hearing my father's running commentary on the Yankees.
Unfortunately, I didn't get a chance to say goodbye as you did which makes it all the more painful. On March 25 it took him 10 minutes to climb the stairs and he was breathing very heavy. He said that he had chest pains the night before so had taken two nitroglycerin. It took until the afternoon to convince him to go to the doctor. When the ambulance arrived at the hospital he was brought in and sedated shortly after. He was in cardiogenic shock with a heart rate over 200 plus no detectable pulse. The doctors managed to bring the pulse down by shocking his heart. Later that day a specialist came in. It turned out that two out of three arteries to his heart were blocked (one had been from his first heart attack in 1989). The window of opportunity to open the second artery had passed since he waited too long to go to the hospital. He had been lucky to have survived his first heart attack despite waiting six days to call an ambulance. This time around all that could be done was to put him on maximum life support and hope that he could eventually be stabilized for open heart surgery. Of course he remained sedated so we couldn't say anything to him. Over the next few days they needed to shock his heart occasionally to keep it from racing but his blood pressure remained very low. At 11:45PM on March 28 he went into cardiac arrest. The doctors were unable to bring him back. To make this all the more tragic he died very young. He would have been 72 on October 2. His mother had actually died less than four years before him at the age of 87.
While I saw this coming over the last year because his weight, poor diet, and lack of exercise was making his physical condition deteriorate to the point where he was in bed 15 hours a day and sounded like he ran a marathon climbing a flight of stairs, I didn't expect that he would go so soon. After all, his mother took no better care of herself (she was 300+ pounds most of her adult life) yet lived to 87. Her brother, who lived a similar lifestyle, lasted until he was 83. I never expected my father to live to be 100 given the way he took care of himself, but I figured he probably wouldn't go for at least another ten years. I just wish I had been able to say goodbye to him.