@collagen Being called ugly is less of what was said but it was definitely implied. The wound, however, wasn't necessarily caused by being called ugly but the fact that Marie as a person was basically being run into the ground. She's a servant, sure, but she was being talked down to like she was worse than horse shit without any precedence. With that said, Marie is by no means ugly(to us readers anyway), but when someone attacks one's character in such a way that the attacker's words get behind the victim's defenses then it can really hurt. Also, I think it was the way it was said that hurt more, since this bitch definitely knows how to get underneath someone's armor with her words. Far as I'm aware, Marie doesn't hate herself in any way and likely does at least hold a little pride in herself as a woman, so having what pride she does have so savagely attacked isn't fun in anyway.
@nivinator I don't think she necessarily has feeling for the (masked)prince, but she is familiar with his unmasked persona(and she has yet to realize the two are one and the same) who she may or may not hold some affection for. As you say, though, she does seems to hold some respect for the prince in both forms just in different ways.
TL
R She basically said Marie is rubbish as a woman and that even the rumored vicious prince wouldn't want her as his concubine, let alone his queen. It's a swift kick in the nuts, is what it is. And at that point it's less about winning(which Marie doesn't care about) and more about how shitty the opponent is being towards someone who isn't trying.