I think instead of inviting her back to teach him, it would be better for <b>YOU</b> to teach him what turns you on and how you like it the most. If you invite her back, no amount of communication will stop his loss of pride. There is absolutely no reason to regret a good sexual experience. He should be proud that he found out you could multiple orgasm's and this is where you need to console his pride a bit. We men are prideful creatures and want to be the best at everything..especially the sexual world. So, what better way to make the sex better than playing games and exploring how you can make your sex life better between the two of you.
After things get a little better then I would say you're safe to bring another person back into the picture. For now, my advice is to just make learning fun. Surprise him when he gets home from work. Dress up in his favorite costume and pretty much just pull his junk out of his pants when he walks in the door. If you have kids then that might have to wait but that will do wonders for his pride and he might just be willing to learn a few new tricks
Oh and regrets are dumb.. you had fun. Leave it at that.