I wasn't horribly impressed by his description of it as "lashing out", either - if he'd punched her once, that would be apt. But pushing someone to the ground and kicking them so hard you break their back isn't "lashing out", it's - I don't even know if vicious is strong enough.
Malicious might fit the bill.
Something about the combination of people and damaged spines really bugs the hell out of me. More than say, an amputation or internal injury.
And it is not Okay, to just say your sorry and hope it gets swept under the Rug, Mr Veitch (gonna have to take away the Mr, because he isn't a man)