AITK for beating up this guy ??

So i 23M and my sister is studying in 11th grade

So there was this boy who proposed my sister and she rejected him ,,immediately she told me about it but i didn't take it much seriously i told she could have rejected him in a less hurtful way

Days later she started complaining about this guy being creepy and following her in school That too i ignored thinking she might be exaggerating

After some days this guy started chatting with my sister on insta and one day he send her a dick pic after which she blocked him...

And then he and two of his friend's started making comments at her during school... which angered me becz this was the limit and i gathered a group of my guys and beat him up and his one friend after school i wanted to break that guys jaw ...but didn't do it as my friends advised me against it (I couldn't get his 2nd friend )

Now after beating him up i am feeling bad for him becz i and my friends beat him up very bad although he deserved it i think we went a little overboard

Now our parents also know about this incident becz school management got to know about this and our parents are angry at me for doing this saying they would have easily resolved the matter ...

But i know for a fact they would do nothing as they consider my sister a liability

I am not a violent guy and i despise these violent movies also i consider myself as a kindhearted person Now AITK for beating him up ..does he deserve it ..

Edit : i tried talking to his family but his father was like boys do whatever they want and told his son was still in his youth