Bless your heart. That just sucks! I used to be married to someone like that. The best thing to do is what you think is best. Hopefully he'll get over it. If he doesn't, too bad. What's done is done. My heart goes out to you. It's a sucky situation to be in.
Maybe you could print out some thing for him to read or send him links in an email. Would he go with you to the vet and have the vet explain things to him?
I wish you all the best.
