Is it possible he could have choked on something, like a toy or string? Did they do an autopsy to see what the cause of death was? I am so sorry you lost Shadow but I don't think it was anything you did wrong. Unforunately these things happen. I hope you feel better soon. I think you may need a break Aly. These things can take a toll. Maybe take a week off at the shelter and focus on yourself and your pets/fosters already in your care. You need time for youself too, time to heal. Please, just please make sure you take care of yourself too.