You have to start thinking positively. You can't think "I'm never going to do this or get past 200," instead thing 'I WILL do this, I WILL get past 200 and all the way to my goal."
Screw the people who say you're fat - who are they to be able to put you down like that? I'm not going to say "ignore it" because that's not easy, but just try and push past it. I don't like looking in the mirror, either, but I force myself to do it. I don't like that my tummy is soft, but I like that I can see that my collar bones are coming in, and that my face is thinning out - don't focus on what you DON'T like, but focus on what you DO like.
You have to become your biggest cheerleader. Tell yourself that you can do it, that you will do it. Don't say "I'm going to try to be better" just say "I'm going to be better at this!" It gives you no option of "failure" if you will.
And you can do it. And will do it.