Sorry OP, I have only read the first page.
Can any of the mums on here who think that the OP's DD shouldn't have defended herself, tell us exactly what she should have done please?
Should she have stood there just taking slap after slap after slap? Should she have turned her back on the bully and tried to walk away, not knowing if she was about to be attacked from the back? I always told my children to never start a (physical) argument, but yes to ending one, as quickly as possible.
@Pointlessworrying I am sure that many others here have already suggested this, but just in case they haven't, please, with the inclusion of both your DD, and your DH, discuss which Martial Art would most suit your DD from the ones available in your area. Then encourage her to attend lessons in it, as it not only teaches good self-defence practices, but also a very strong self discipline attitude. It should also instill a confidence in your DD that is great and necessary in it's own right, as well as the chance that she may emit an aura of self assurance - thereby hopefully alerting the bullies, and any possible future rapists or murderers, or even possible future gaslighting partners, to leave her alone.
Or rather than choose one of the Eastern Martial Arts, she could take up Boxing. My only concern there would be if she got the bug for contests, which could lead in the future to her boxing without a protective helmet? I don't know enough about modern boxing to know if fighting - or training - is ever allowed without a helmet these days, but to me that is a massive negative to the sport if it is.
If none of those are attractive to your DD, at least insist - through bribery and corruption if necessary, or circumspect removal of certain privileges, such as not being allowed to go and meet her friends in daylight, on her own - that she attends general self-defence classes.
I really believe that all girls and women should be taught self-defence, and also that sons like mine, that wouldn't say boo to a goose, and who would not have any idea or inclination on how to defend themselves, or others, should attend self-defence classes also. Maybe, as mothers, if we are also hopeless at things like self-defence, and sticking up for ourselves, we should lead our DC by example?
If things have not yet been sorted out agreeably enough between you, your offspring and your husband, then I hope the suggestions on this thread go a long way towards that end. This really does need sorting out urgently, please don't let it end up being brushed under the carpet, which seems such a reasonable and comfortable place for the dust and dirt to sit and be forgotten about - until one day the carpet needs to be raised, and all that dirt blows up in our faces... 🧹🧹🧹