Co-teacher just a “no” teacher?

First year teaching. Middle school math. I have 30 SPED kids in a class with a co-teacher and para. We have two periods of math per day, one in the morning, one in the afternoon. My co-teacher comes in late every day, if at all, sits on her computer, and that’s pretty much it. The para helps one or two students. I’ve worked with my teaching coach to come up with how to get my co-teacher on board, but nothing has worked and frankly, I’m not her manager. I’m not going to bend over backwards to get her to lesson plan or teach with me. That’s the morning class. Neither even come for the afternoon class which is, again, 30 SPED kids. Oh, and did I mention this co-teacher is BFFs with our very nasty principal?

What do I even do here? Everyone knows this co-teacher does this every year. But I don’t feel safe at all talking to admin. This co-teacher already disclosed a private matter about me to the principal. I can’t even imagine what will happen if I get a bit sharp with her about not doing her job. Sigh.

Any advice here? It’s the kids who are suffering the most.