IIS SHE A TRICK?WHAT DO U THINK?

I've been with this girl 4 years were both 18 but i just got a realization today.i think she's a trick.she does things like buys some sexy lingerie and tells me its all 4 me then posts pictures of her in it on the internet.she tells me I'm all hers then puts videos of herself booty shaking on the internet.she says shes my wife but takes provacative pics with guys.she once let me get jumped by her brothers when i got caught in her mothers house while she watched.she doesn't see me anymore but tells me she misses me.she says she doesn't talk to anyone else but on myspace guys are calling her baby.on facebook she's always talking about sex or making posts like if we were at a party i would.and expects guys to answer but she tells me she doesn't feel the erge to have sex. She goes out to clubs. She has a guy friend i know about and its her sisters baby daddys brother.she made the bootyshakin video and comnented saying.i told u i can dance better than u. So that tells me she sees him but she tells me she stays in house all day.idk wats going on or y she stays with me please I'm lost. Please b open and tell me if u understand me and what you think and y.