First of all, I am sorry this happened to you. People will be mean, as said above, no matter what age, no matter the reason. With that said, however, I am a down to earth, no sugarcoating type person, so please do not think I am intending on being mean myself with what I am about to write, however, please consider it.
You're feeling down and insulted for being called a "guy" and you're allowing it to sink in. You're a woman; a woman would shrug this comment off, think to herself that those girls were simply jealous and crazy, and move on with her day. By you letting this get to you, you're only subconsciously admitting to yourself that you are still a guy. Let me say it again, you are a woman. You are not a guy. I understand the hurt - I've had it myself, but you have to rise above the pathetic comment that girl made, you're better than that. You are a woman, stay confident.