What is the best thing to do?

ok it's kind of a big story but PLEASE read it 'cause I desperately need answers!

OK SO: 2 years ago, i went to high school. There, i made new friends (Stef, Kathy, Theo and Con.). i liked Con very much and after a few months we were in a relationship. sometimes we had big fights but we knew that we liked each other very much! once we had a HUGE fight and after that, i broke up with him because i thought we didn't match. but since then we are best friends and we are having great time with our other friends. con maybe likes another girl even if he didnt tell me, i am sure there are more beautiful girls than me and he would like one of them.

No one knows it, but i still like him. But i don't know if he still likes me, because i am more ugly than last year. i put on weight (9 kilos - because of a health problem) but now i am trying to lose weight again. i really want him to like me but i dont want to be pressure so i didnt tell anyone. But a couple of days ago i learnt that theo likes me, but i really dont. he's a good guy but usually REALLY annoying. i would never have a relationship with him, but IF i have one with con again, i think he will get hurt. not because he likes me, but because no girl likes him! :/

but my big problem is con. what do u think i should do? and what is the right thing to do? i dont want someone to get hurt! nor me, nor con, nor theo!

advice please? :)

thanks!