Time to Quit?

Today I went to my job at the home furnishings store. I've cut my hours back to only one day a week now that I work full time at a make up counter, and honestly the only reason I haven't quit is because I enjoy the safety net. I like knowing that if I quit one job I still have another job waiting in the wings, but today really made me think about quitting.
When I arrived at work, my boss was there (which she usually isn't) and I went out of my way to say hi and exchange pleasantries. Did she return the favour? No. She immediately demanded to know why I wasn't at the staff meeting last night. Why wasn't I at the staff meeting? Because it wasn't on a Monday. DUH. I only work here on Mondays. You know this. I've explicitly told you and put through paperwork to make it abundantly clear that I'm only available on Mondays. When I told her I was at one of my other two jobs, she didn't let it go. She wanted to know when I was finished. When I told her six, she told me the staff meeting had started at 7:00. Uh huh, but here's the thing: I only work on Mondays! I don't care what time I was done yesterday, I wasn't coming to work after.
Thoroughly disgusted with her lack of tact and common sense, I started my shift in a nasty mood. Which got me to thinking, why am I still here? Aside from the coworkers that I adore, why do I bother to hang onto this job? Yeah, the extra money is good, but it only amounts to an extra forty dollars a week. That's not really worth how irritated and bored I am with it, or the fact that I'm working six days a week (aside from my restaurant reviews) to keep it. Maybe its time to let if fall by the wayside and move on. Maybe its time to quit.