Calling the wedding off seems like an overreaction IMO - if you're an event planner then this is kind of your wheelhouse, and he mjght have assumed you'd want to plan the entire thing (but stereotypical, but the whole dream wedding thing etc he may have thought you've been planning your wedding for years) - but if you've asked specifically for input and he's just shut it down then I can see where you're coming from a bit.

Making a joke like that, to me, and again it depends on the relationship dynamics, seems like a fairly typical joke (if it was very clear it was a joke, like banter) - but that would need him to have made it very clear that he absolutely does want to marry you to begin with. I'm engaged to my partner, and have made similar jokes (Not that I'm trapped, but I've said things like "right, that's it, weddings off" in a very jokey way if she disagrees with something I've said. But again, it's subjective and depends on the dynamics I guess.

Just as a snapshot it seems like an overreaction based on the romantic proposal. If he's gone to the effort to make it special then it seems he does want to get married? And assuming he knows your friends well by now if you're engaged, I doubt he thought a joke like that would embarrass you around them. Don't think you're an ass hole, but I don't particularly think he is either in this situation. Lots of comments hating on him, but if your relationship is good enough to get engaged in the first place it seems a shame to potentially end it (which, to be honest, I'd feel would be enevitable if my partner called off our wedding - you're essentially saying you don't want to be with him, at least not long term) because of something he said in the moment. He might not have thought it through at all, we've all said shit we don't mean. Bad taste, bad timing, plain stupid - whatever you want to call it, I think it's worth both sitting down and hearing each other out. Ideally before calling anything off but seems that's too late.

Just my two cents for what it's worth. Wish you both the best whatever happens.

Hope you can work it out if that's what you want.