Am I Wrong??

So I babysit for this family. They pay me 150 a week for two kids. Well recently she her husband got custody of his two kids so now I'm watching four kids for 150 a week. I pick them up from school, make their meals, bathe them. This all seems like a lot for just 150 a week. I tried asking about a price raise, but the mom just keeps saying we will see. Now I let them know my schedule. They know I have late classes on Fridays. But they are both usual off so it's okay. Well yesterday I get a text in class from the mom saying she's stressed out and needs me to take the kids to the park so she can have a break. I tell her I'm in class, she basically is trying to get me to leave class so she can have a break. I flat out tell her no and we get into a text argument. She starts blubbering about her no one cares about her. Like why are you telling a 19 year old this, go talk to your husband. I'm just sick of her. The pay isn't good, I'm being bitched at for not leaving class. I'm just sick and tired of everything.