Everyone at school hates me now? Do you think what i did was wrong?

[Babyface]

Saying the truth is right but hurting and making people angry is wrong.
In a way you are both right and wrong.
Usually it's best to keep your mouth shut when you see the ugly truth. Next time don't do such things. If you are ever going to do such a thing, don't do it in public. Never ever. It'll end up giving you a bad image. Esp. when people say nice things about them.
Yes that girl did wanted attention. Right now, you can't take back what you said. So you'll have to defend yourself when they say mean things about you. Be cool. Don't hate anyone. Don't let hatred get the better of you. When people talk about how bad you are for saying that tell them what you said was not wrong. Be polite but firm in your speech. Don't get into an argument and end up saying mean things to them and using bad words. Tell them you did told her she's not ugly. You didn't said anything wrong. Everyone knows she is hot but how come she doesn't knows? She should be more aware of herself than others. People are always aware of what they are and what they want. Why doesn't she believes she's pretty when she is? A normal person would never call themselves ugly if they know they are pretty. It's irrational and can only be interpreted as calling for more attention. She was wrong to call herself ugly. She shouldn't have called herself that. Tell them if they think you are wrong then they are narrow-minded. What does narrow-minded means? You should know this otherwise you can't call them narrow-minded. Being narrow-minded in simple words means that the person only focuses on one point (here they are focusing on that girl) and they never try to or attempt to understand anything other than that (here they are not trying to understand you). This is the reason why narrow-minded people are bad judges because they don't try to understand everything. They only try to understand what they like. A broad-minded person will listen to everybody's side of story even if they don't like that person. They are more likely to be good judges. They listen to everyone before judging and treat and respect everyone equally.What's more is that they make us realize our mistakes. The only problem is these people are less and narrow-minded people are more.
Tell them that you are really hurt and can't believe you thought of them as your friends(if they are your friends). Tell the same to your bf and sister. I think the reason why they are not on your side is because many are on the her side (the girl who caused this problem). I have gone through stuffs like this a lot. That's why I can see that those people who are against you are narrow-minded. I had to defend myself. There were very few people who were on my side. Like you, my sister too didn't take my side. She just didn't tried to understand me. I stay cool when I defend myself. I never let hatred or anger get me. I know that if I succumb to it, I'll make wrong decisions. I only speak what I believe in. Whenever I'll speak I control my anger and emotions and do my best to be polite and understanding. Though sometimes, I'll end up crying.
So you should do the same. It's best to avoid fight anyway.
So be polite all the time when you defend yourself. Be in control of your emotions. Talk about this with your mom and dad too and a close friend. If they don't understand, tell them you're hurt. If they understand be glad that you are not alone.

Take care.