people are spreading rumors that im pregnant!?

Im only in 8th grade and im a good student and never get in trouble. i never fight with anyone. well there is this boy who always picks on me and my "friend". he called us ugly and fat and we told him to look in a mirror because we were tired of it. he started telling everyone i was preganant by this boy i never talk to! all my friends wont talk to me. some teachers know and wont look at me the same. i started crying in 4th period and went and cried in the bathroom until the day was over! i know i shouldnt be so sad but everyone is gonna hear it! what ahoukd i do its not true.