Overreacting?

So me and my best friend drive to my house to eat lunch every day. I always drive because I have a car. She’s my only close friend in school. But the other day, she lied to me and said she wasn’t at school, when she actually went out with her other friend, who treats her poorly and she constantly complains about.

I don’t know how to feel. I don’t like that she lied to me, and don’t understand why she would do this. I also feel kind of used, because I always drive her around and give her food, never asking for $$ in return.

How should I feel about this?