I don't know how to get rid of this thing?

dude, if you were suppose to be going out as BF GF and she went to help her uncle without saying a word to you... that would be so disrespectful. Her so called" helping her uncle" story seems like a train load bull #$%@. Maybe her bro is full of it too. Dump her like last weeks diapers. There are so many other girls that know what respect is. Forget about her. Life is too short. I dont know your living status or if you see her everyday, but I think it's time to move on. You might be in the primary stages of a domestic violence candidate or worse. Change girlfriends before it's too late.