I can sympathise, my DD turned into jeckle & Hyde around 10yrs of age & it drove me nuts. I ended up being very restrictive on what was acceptable behaviour & we both attended sessions with a social worker who specialised in children. This taught DD to recognise why she felt they way she did & taught me effective communication so not everything was a battle. It turned out my DD also suffers from anxiety which was causing her to lash out.
Now she's 12 & things are much better - she still has normal preteen mood swings but it's manageable & since I've been pregnant she's taken on more responsibility around the house (even does her own washing!).
I'm not suggesting therapy is what you & your DD need but it worked for us & has paid off.
Good luck, it's hard & it's frustrating. I even got to the point where I'd dread picking her up from after school care incase it was the monster instead of my beautiful DD getting in the car.