The reason she is hurt that you think she is dictating to you, is because she is dictating and she knows it.
It sounds like you're doing really well, tbh. I think the main way to change your reaction is to get more practice at standing up to her. And find some other people (RL, or on here) who can listen to how your last encounter with her went and show you by their reaction that you were behaving well and she was not.
Honestly, loving mums do not look at the wedding dress their daughter is thinking of and say "that's vile you have no taste you will look awful in that". They swallow their opinion and say "how lovely dear, you know you'd look beautiful in anything". Unless you've chosen a lime-green meringue-dress made of polystyrene and clingfilm, I suppose, then she may have a point ...
You could try "that was rude! Did you mean to be rude?". Although she won't accept that she was rude, because you're her daughter and she can say what she likes to you - you don't have feelings, or not any that count. But you may as well plant the idea that it is possible to be rude to one's child.
Also the "water off a ducks back" method. When she goes off on one and starts being all injured and hurt that you aren't her clone, smile brightly and comment on the weather. Or, if possible, announce that you have Things to Do, and leave swiftly. Its what you do with toddlers in a strop, after all - remove your attention.
And see less of her, of course ...