I am so sorry for your loss. Our girl, Brooke, died on her pillow while we were at work and the "not knowing" was horrible, so we had a necropsy performed. I found it helped me get some closure although it was incredibly painful even though there wasn't anything we could have done. I still felt so guilty for not knowing she was sick. I imagine the outcome for Merlin would have been the same and unlikely that you could have prevented it. My heart goes out to you, it's clear in your post how much you love him.