One of the perks of being an adult is that we get to move away from parents who may be toxic, who've gotten to take out their stresses and angers at life on us because we happened to be their family members. And while we are minors, there's no place to go and no real protection from this. When we become adults, we can get away, we can join the military, we can marry, we can simply move out and restrict our contact with those others who behave in toxic ways toward us.
You are not your stepfather. You are not married to your mother. And eventually, you can get away. However, you do not sound well enough or able enough or self sufficient enough to do that at this point. That's what you should be angry about, and working to remedy, not that she's the same person she's always been and she's extremely frustrated with you, and she's sharing her feelings with you. Not spending time plotting about having a case against her for mistreating you to be heard in court somewhere.