Ok, you also need an attorney, or you might find yourself out of a place to live. The fact that he did not serve you with a 30 day notice is a defense, but the Judge has to believe you over your brother. Also, if your brother does not own the property, he does not have "standing" to bring the unlawful detainer. If he says he's the agent for your Dad, that's a fact that needs to be proven.
Seriously, hire an attorney for this. Your hearing Monday is known as a "trial" and trials are difficult to do without knowing the rules of evidence.