Can we stop with the suggestions of how to scale back this wedding? She doesn’t want it and it’s not about the money.
The way I read this is that along with the anxiety you feel guilty because, probably in that flush of early wedding enthusiasm, you were the one wanting a big wedding in the first place. You talked him into it and now you don’t want it and he’s pissed off probably for the same (understandable) reasons you are - being embarrassed, social pressure, “looking stupid”, letting people down, all that nonsense. For both of you that sense of being on an unstoppable train towards a destination you don’t want is truly awful.
You are allowed to change your mind about things. You are allowed to get it wrong and make a mistake and decide to do something different. That happens to people in different situations all the time. It is human and normal.
If you can really get your head around that I think it will help. You’re getting confused because you’re paying so much attention to what everyone else thinks at the expense of what you want. But what is needed here is a clear assertive statement of your wishes from you to your DP followed by action. Stop asking him to take the lead! “I feel like an idiot and I know this is hard but I made a mistake. I don’t want this wedding any more. It’s making me anxious and unhappy and I’m going to stop planning it. This has absolutely nothing to do with how I feel about you and I would really like us to make alternative arrangements to get married. I will take the lead in cancelling things.” And then just do it. Then the decision will be made and you can move on to the next stage, whatever that is. I’m sure people here can advise on what to tell people but the initial action has got to come from you.
Will it be awkward and uncomfortable for a while? Yes. Will you all get over it? Yes. And so will everyone else including your partner.
I cancelled a wedding AND ended a relationship. It was very hard indeed but everyone came through it ok. You will too.