Ugggh how can i get rid of this really obnoxious lady?

Hello everyone. I'm in high school, and i'm experiencing trouble with some annoying moms bragging about their kids. So, I go to Arabic tutoring (My grandparents live in Egypt,) with my sister, and there's this family that used to come with us, but don't anymore. We paid for private tutoring lessons, and they would ALWAYS show up 20 or even 30 minutes late to the private tutoring. The lady would make us stop at 12 because she had other things to do, and so basically this family was making us wait for them, but we still had to pay. And that isn't even the worst part. My grandfather died last year, and we still went Arabic school anyway. My mom told the mother of the family that he had just died, and said "oh really?" and just started to talk about the Egyptian pyramids and how it's a pity we've never gone to see the pyramids while we've been to Egypt. So during a presentation of our Spanish progress over the years, the mom mentioned in the congratulatory remarks that her daughter was fluent in THREE languages! She tells everyone that and it pisses me off so much!!! They haven't come to the Arabic tutorings for over a year now, and when they left, we were still learning how to read and write, let alone speak fluently. She always amde up excuses about why they couldn't come. I speak pretty fluently because i speak to my grandparents all the time, and we see each other a lot. My mom doesn't go around saying it, and this girl can't even read and write!!!! She also went around bragging about how she just graduated from a community college, and the dresses her daughters were gonna wear. (it's for her bachelors degree.) My mom doesn't talk about college at all, and she went to Yale!!!!! She also treats me like I'm stupid just to make her daughter somehow seem smarter, even though i'm a better student. She also thinks it's lame that i like to read Harry Potter and Shakespeare because that's not what cool teenagers do. How should i deal with this lady?