I'm annoyed when my so calls to vent about work
Why don't you like her venting about work?
I asked her what she meant with her statement and I got the answer that I didn't want.
Being a significant other means that you are a source of social support. You should listen when she calls because in those moments she needs someone to talk to. You should always show support to those you care about, the same way that you would want them to be supportive to you.
I'm going to respond in a very rude and unsupportive way.
I don't think you should be rude to her. Almost every couple vents to one another about things they don't like.