My Husband David died today

David died today. I went out for a couple of hours and when I came home I found him in his wheelchair leaning forward, like he fell. When I pulled him up straight his face was black, his skin was cold and he was not breathing and had no pulse. Whatever happened, it was quick. I think he might have dropped his phone and tried to pick it up with his reacher and maybe fell forward too far. He would have been on the floor if he had not had a seat belt on. I know he could not have pulled himself upright, he was not strong enough to do that. I'm sad that he died alone, though we were only gone for a couple of hours. I'm in shock. David was 68 years old.