My DD went through a similar episode in the autumn term and HOY came down hard and fast. DD's experience taught me that when it escalates that fast, it tends to disappear again as quickly, and although it's bloody awful for a few days, it's preferable to the long, slow insidious bullying that destroys your confidence.
It's good in a way that they have broken up, because they can let the dust settle, but on the other hand, she's now got 2 weeks of dreading going back, because she hasn't had time to witness any positive changes.
Make sure she knows that the HOY is backing her and dealing with it, and the first sniff of trouble on the first day back you'll be back in there and demanding results.
I'd also take a few minutes to write down the events of this week - just so you've got an accurate record of what's happened, and can compare the school's actions to the anti-bullying policy. We did this. We didn't ever need to show it to anyone, but it helped me and DD to feel we were being proactive, and it would have been there had we needed it to refer back to.
Another thing - I took away all means for my DD to be contacted out of school - ie no facebook, no phone, no texts. She essentially went off grid. I imposed this on her, but made it clear it wasn't a punishment, I just took the battery out of her phone and switched it off, and disabled her FB. She put up no resistance and it seemed to take a weight off her shoulders.