Would you be mad in this situation?

My bff says I am getting mad for no reason. First of all I called her on Friday to see if she wanted to hang out with me and she said I can't I have to work. Less like 10 mins later, I go onto Facebook and see that she just posted pictures of her hanging out at an amusement park with some other friends of ours. Then today she tells me that she is sick, but posts pictures on Facebook of her at the mall with her sister. I feel like she is trying to avoid me and I am mad that she flat out lied to me when she could have just said, no I'm hanging out with so and so today. I told her that I am mad at her and she thinks I am getting mad for no reason.

Would you have gotten mad in this situation?