I am so sorry for your loss. I know it's hard to lose a furbaby that's been with you for so long.
I lost my Neechee (age 17) the Monday after Easter 2010. He had had multiple strokes, but this one was bad - he was in pain. He, too, died in my arms at the ER vet. I still miss my little guy, and it seemed like my heart broke that day and will never be fixed.
I'm sure your Morgan will be waiting for you at Rainbow Bridge, and Neechee and my Border Collies and cats will all be waiting for me. It's so hard to lose each and every one of them - they all make different places in our hearts that will never be the same. We just don't have enough time on this earth with them.
Your Morgan is no longer in pain, no longer suffering any bodily complaints. Where he is he is always young and full of energy and ready to play!