He called me fat

There are certain things a husband should KNOW how to say to his wife.
Timing is also very crucial.
A husband never say to his wife;
" Lie down and open your legs" when he wants to have sex.
He skilfully initiates.
Just like,
A wife is not supposed to tell her husband that his penis to too small for her pleasure, he will feel insulted.

So that
A man who criticizes his wife and tells her she is too fat just before they attend a wedding, when she is trying her best to look beautiful by his
side , is very inconsiderate and insensitive.

His timing is bad and he was rude.
It sounds like he has issues with not caring what other people think.
If he were more confident, he would have told you that you looked beautiful in some way and not mentioned your weight, and then had the pleasure of being with his wife who was 'shining' during the wedding. Instead, he contributed to what must have been a dismal day when you ought to have been celebrating a union of two people in marriage.
Some people know how to create a positive world around them.
It sounds like your husband could use some more practice with that.
If he were concerned about your weight, he could have talked to you about it at a more appropriate time, and if he were concerned about appearances, he could have gone shopping with you for an outfit and had some say in how it looked.
Fail!

First question, did you ask him how it looked and what was his exact answer?

The reason I ask this is that first, I don't ever ask my husband, 'does this make me look fat, etc'. IF I want his opinion, I'll normally ask, which outfit/dress/etc. do you like better?

I don't ask if something makes me look fat because it puts him on the spot. Most men don't know how to reply/respond and we end up getting angry or hurt with almost any answer other than 'You look beautiful'.

I can also state that if I don't feel good about my physical appearance, I judge his commentary a lot harsher than it really is. For instance, when I was losing that god awful 50 lbs I had gained, I made a comment about buying a cute corset with garters, stockings, etc. My hubby said 'Why don't you wait until you lose the rest of the weight'. All I heard was 'You're too fat for that' which was clearly not what he meant. He's since learned to phrase things a lot smarter too.

That said, if he said 'You look fat', I think it would be fair to have a discussion about how rude that was and inappropriate.

My husband never tells me I look fat. He tells me I am beautiful and sexy, and I tell him the same thing, because despite the fact we're both carrying around a few (ok maybe more than just a FEW.............) extra pounds, we both really do find each other sexy and beautiful.

Him telling me I'm beautiful makes me want to look good for him, WAY more than it would if he told me I looked fat. When I complain to him about my weight he complains to me about his and we both agree to get on the treadmill more than once a week and not have beer with EVERY football game. And we do for a while. But we've both been the weight we are for a few years now, and I don't see anything changing soon, but we're both happy with things the way they are too.

If your hubby isn't happy with the way you look, he should try to help you change it or shut the hell up.

Only 2... correction... THREE occasions when I'm blunt like that, first is to get a reaction from my wife, but obviously I would use the usual jokey/teasing tone of voice so she knows I'm poking her not insulting her (much hehe)
The second occasion is when she wants my honest opinion so I give it to her.
The other occasion is when she just looks absolutely WRONG in it so I will voice my disdain rather brutally honestly lol - but that's rare, she normally has a good taste of fashion

The thing is though my wife has no trouble losing her weight so it doesn't really bother her that much but I guess I can see how if she did have issues and I said something like that - well that's just rude.

Have you considered pole dancing? It's how my wife lost her weight FAST, blinked and walla "where the hell did all the fat go?!"

It's pretty obvious the women here are pretty sensitive about weight. So I have to assume that there is a lot more to the story that the OP neglected because it would compromise her being the innocent victim.
I can tell you from personal experience that a man wants a wife who dresses for her weight, especially if he is going to be around all of his friends or family. I posted in a thread a while back that my wife would constantly wear clothes that were a size too small, and it made her look like crap. She would have looked much better in the right size, but she refused to buy that next size up because that would mean she would have to admit her weight to herself. I would never be stupid enough to bring it up right before a wedding, which is why I have to believe there is more to the story. Maybe the OP missed nicer and more subtle hints prior, like when she bought the dress. Maybe she bought it small with the intention of losing weight to fit into it, but never did.
A women being overweight doesn't just affect her, it affects her husband who looks at her far more than she looks at herself. Some men are perfectly fine with their wives putting on weight, but some men are not. Neither is wrong. Each spouse has an obligation to try and look attractive for their spouse. Women don't feel any different about a man who starts out fit, and then gets fat. It's a turn off to many.
So the bottom line is that your husband is trying to communicate, but doesn't know how, or feels like he will get his head ripped off no matter how he does. He might need some lessons in communication skills, but he has something on his mind that shouldn't be ignored.