Another restorative hug for you ((((Boomer))))
I admire you so much for your earnest trying to make it right for little Mo.
I think you've already had great advice and I particularly love everything that Noddy has said. [Hold your Dominion, yes!] I think Mo is feeling conflicted and seems obviously stressed to me.
There is only one thing I can suggest which doesn't seem to have been mentioned -- the litany of all those you love is such a good thing, but here's something else.
Before he goes, make sure he knows that there is something delightful planned for when he returns to you. Maybe it is making peanut butter cookies or ants on a log. Maybe it is going to a film or taking the dog for a walk. Give him something he can hang onto when he's there, some homey memory of you, because you really are his home.
How's that stupid rat, Winnie, doing? Badly, I hope.
Ahh, maybe it is good to have something to hate.