Frustrated with work

My first job after graduation has proved to be difficult. My don says we're staffed appropriately but I feel like that's completely off basis. I work two jobs and both are part time. I work 12s on thurs and fri at one job but this new job I have likes to schedule me 12s sat and sun, and 8s mon and tues... knowing I've already worked the two days before. 64 hours straight has become much and I've expressed my feelings about that. They told me that a static schedule is the gold standard but it never works that way, basically because this is "the real world."

Not it only with scheduling but I have two children who take a lot of attention and by the end of the week I get really tired. My don has told us that we are responsible for finding our own coverage which puts us in a terrible position. Nobody typically wants to cover and then you are forced to call off if something happens or in my case pushing myself past exhaustion to work anyway because I don't want to get fired. You get 2 call offs in a 3 month period and the third is a termination. I never can find coverage for any dates, even just partial shifts, short notice or future notice. Our prn nurses don't like to pick up shifts and neither do the full time because they are frustrated themselves. I'm not sure how we are expected to find coverage ourselves. Sometimes I get straight up ignored.

Has as anybody else gone through this with a facility? How should I approach this again?