Oh man. I'm sorry you're going through this.

First off, I would not go to Florida. Warning bells went off in my head as soon as I read that and I'm not even a part of the situation, haha.

Here's my take on it as a completely impartial (blunt) third party: His family is incredibly controlling and involved in his life, and that will never, ever change. Not now, and not after you marry him. I don't think that, if they've formed such a strong opinion of you before having met you, they will change their opinion much after meeting you and that has nothing to do with you personally--they seem to view you as an intruder/usurper who is taking a bit of control from them, and they are reacting against that, not you.

I think you need to decide whether you are willing to take all of that drama and headache on for the rest of your life. I am not currently in a relationship so it is easy for me to say that there is no one who is worth my peace of mind, certainly not for the rest of my life. I have been in a relationship that hurt my mental state to the point where I ended up hospitalized. Having been there, I will not be part of a relationship again which compromises my mental health, and I would advocate for you to put your health and sanity first no matter how important this person is to you. You are the most important person to you--it makes life simpler to remember that. Besides, if you're not in a good state, you can't be a good partner.

Lastly, I think it is incredibly unfair that he doesn't seem to be standing up for you. I'm hearing you say that he considers your feelings, and I understand that these people are his family, but when they are being so awful and disrespectful, there has to be a point at which he says something to the effect of, "Enough. This is the person I have chosen and love. That is my opinion, you may keep yours to yourself." I may be wrong but instead, it seems as though he is attempting to appease them. I know I'm not you, but I don't think I would be okay with that, especially knowing that it would always be this way. At some point, he has to put his foot down with his family.

That's my take on it.

Edit: I come from a Catholic family as well. We're not about public shaming over revealing outfits. That isn't a Catholic thing, it's a nastiness thing.