I know a lot of girls who just call everyone hun or sweetie, sometimes I slip out a sweetie at the end of a sentence, but that's pretty rare.
If it bothers you that much, talk to her about it, if she's not a real flirt she may not even realize she's doing it as much as she is, some people are just like that
But if you feel worthless in the relationship, is it really even worth being in it?