I'm SO fed up and stressed from my job!?

I know I'm going to sound VERY whiny, and I know I'm being immature. But I just need to rant. I get SO many customers working at ShopRite every day and all of them are SO rude. If I greet them, I get a blank stare. I get their Shop Rite card shoved in my face. I get questions about why something is so expensive, when I'm just a freaking cashier. Like, why are you asking me? I'm just a teenager trying to work. I got SO many rude customers that after work I drove home and sat in my car for 30 minutes crying in the hot car when it's summer outside. Has anyone ever had to deal with such rude people? It's not just the customers. My manager is sneaky. My supervisors talk **** about me and don't want to help me. My coworkers ask me to drive them home and treat me like ****. What the heck? I know there are SO many more stressful jobs and being a cashier should be no big deal, but I don't know...if I'm being treated like **** every day by more than half of my customers and everyone else..it doesn't feel good.