Prévention is better than cure. Once in the meltdown/tantrum phase no point talking she is only responding to emotion and physical. For some kids a big hug works. (Deep pressure) (but only if they are not going to be able to punch/bite/scratch/headbutt and at 11 it is a bit trickier to manage this safely if you have not practised on a smaller kid. )
But spotting the signs, intervening early, disciplining when she is calm. (At least an hour after to let the adrenaline clear from her system) (Make her think how you feel when she behaves like that and write an apology)
Praise the good. However small. Look for her being good and praise it. You probably don't like her much now, you need to work on liking the unlikable looking for the positives. Don't pull away when she needs you.
Don't shout. It doesn't work. (You will shout sometimes, we mostly all do which is how we know it doesn't work)
Look up the pop bottle analogy. She's kept the pressure in at school and releases it at home. Just because she is good at school doesn't necessarily mean she is choosing bad behaviour at home. She may have got to the point she can't control it any more. But you can choose to help her manage this. Find a way to release it slowly. She may need decompression time straight after school. (Silence/food/drink/alone time or hug/mindless electronic game/exercise)
Look carefully at everything that happens for the hours before a big blowout. Sensory, your responses, what worked, what didn't what happened at school, Write it all down look to see if you could have done something different. You may need to change your attitude and outlook. You want this to stop. There are no quick fixes. But it will get better as she grows and as you learn to manage the big emotions better.
(It helped me to know mine was autistic so looking up puberty and or any suspected conditions may help you cope with the behaviour. A sort of explanation not excuse. Doesn't mean you don't have to work on changing her behaviour. Just helps your ability to rationalize it and deal with your emotions)
Other things we have done is name the emotions. "That must be so disappointing" etc. Seems to help.
Yeah, and selective deafness, withdrawal of services.
Don't be surprised if she can't remember what she said. This is not uncommon as they switch to the emotional part of their brain and don't make new memories. Also why reasoning with them does not work if in proper meltdown.