I went 2 a party w/ my ex bf's current gf and she sed a lot of stuff that made me feel weird.?

My ex boyfrnd asked me 2 get back 2gehter and i sed i'll think about it.then last nite i was @ a party w/ his current gf and she sed a lot of things that made me think he's lying.but i asked him and she's lying.idk hu i belive.hu should i???HELP!!!!!!!!!!!!