I feel embarrassed for having a job in high school. How should I handle things?

So basically, I go to this really prestigious private school and I'm a senior right now, and about a year and a half ago or so, my parents completely cut me off financially. Even though they're really well-off, they refuse to give me money thinking that I should "work for what I want and need instead of having it all handed to me" because that's how real life works.
Long story short, to be able to move around and do all the things the people at my school do, I have to work two jobs and its STILL not close to enough. It's just so embarrassing. I mean, they keep on dragging me to places I honestly can't afford, but if I say that it's going to be really embarassing and also, it's going to seem really unrealistic because they've seen my house and the way my parents live. The only person I've told is my boyfriend. I can't help but feel ashamed that there's just so little I can afford, and also a bit jealous of my friends, who get to do everything they want. I mean, their parents get them Range Rovers and Mercedes SUV's and all I could afford to buy myself was a used Honda Civic from 2000.
My friends are just making it so hard for me to feel good about myself, and if I tell them I KNOW they're going to make fun of me. They look down on the sort of kids who have to get a job through high school. I already tried asking my parents and failed to achieve anything, I feel like they're just trying to ruin my life.
Any advice? What should I do?

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