Self Esteem

Okay so my New Years resolution was to be more happy with my body and have more self esteem and confidence. I’ve been doing good lately but today I was walking down the street and two boys drove past and shouted ‘FATTY’ at me. I’m not skinny but I’m not severely overweight either and this comment has completely destroyed all the self esteem I’ve built up over January. I feel ugly and worthless, how do I rebuild the confidence when I feel like I’ve been knocked back 10 steps?