If people are laughing at you, making fun of you, and acting as if you're worthless, they're treating you with derision. Derision is mean and attacking — it's a form of contempt.
Derision is more than just making fun of someone — it's mocking someone so forcefully and with such venom that you discredit the person completely. Derision can include literally laughing at someone or just treating a person like a joke. You know how celebrities and politicians do embarrassing things from time to time? They're usually treated with derision afterward: people mock them, treat them with contempt, and try to make the person who messed up seem completely worthless.