Hugs to you.
She sounds a lot like my difficult child. Tantrums where she is cursing and calling me a stupid idiot and slapping and kicking me and then a couple of hours later saying I love you and could I cuddle with her.
It is exhausting and you need to take care of yourself. I recently started taking medications for depression and I did not realize how much of myself I had lost from the constant stress of trying to hold everyone together at home.
We are just starting the medication route for difficult child so I have no advice there.
Sounds like you need respite or psychiatric hospital for difficult child. Hang in there.