Girls i really need your help on this one please help ? PLEASE HELP ?

ok well my gf has been talking to this guy named john and she talks abt stuff she says he s a perv but she lagh s at all he crap stuff he says at first i thought awww just anotha dude hanging out with my girl its cool but he s flirting and she s flirting back im like :O because i use to be a bit of a flirt but i stopped for her i even stopped talking to one of her friends tht she thought liked me i dun wanna tell her how i feel cause she s dealing with alot of crap now days and i trust her that she wont end up liking some other guy somtimes its hard keeping my faith i could have told her about alot of things tht other girls said to me but i dun tell her because i know she would end up feeling bad its like im ******* doing evrything i can to keep her from getting sad and she throws this guy on my face like i wont care she knows how jelous i get somtimes im just really messed up right now any advice would be good thnks all of u for answering my crap problem