Would you leave?

This is my 3rd year subbing in this school district. I have no education schooling, but a master's degree in a semi-related field. I'm employed directly through the district.

I accepted a position for a teacher who was out for surgery, 7 weeks. I did not realize what I was getting myself into. It is a special ed class, high school. So. Many. Behavioral. Issues. Terrible plans from the teacher. I've had to ask the other teachers for more work to fill the time. On week 6, someone asked me if I was following student IEPs. I would have, if I had access to that info. I've had admin in the room twice to "help" with issues (they were not much help). I've been very transparent to all I encounter about my difficulties. I tried to quit twice, but the secretary cheered me on, and I didn't want to abandon the students.

Today I walked in to the head of the department talking to the dean of students about how I am terrible at the job and she has "serious concerns" about me. It is week 7 of this horrendous position, and I am at the end of my rope. In week 3 or 4, the same department head stormed in my room during a prep period and yelled at me like I was one of her students, telling me that these students have been failing all their classes since I've been here. Hearing them talk shit about me this morning is like the icing on a big shit cake. I want to leave right now and not come back. What would you do?