School suspended me after I exposed a teacher. What do I do?

I genuinely need some advice from people who understand how schools in Nepal actually work.
I’m a Grade 12 student at a private school.
Basically, a teacher had an incident with a student where he was yelling at/verbally abusing the student (The teacher has verbally abused and beaten several students, and his behavior is unpredictable). A friend of mine recorded part of it.

The video ended up spreading. First it was around 70k views, now it’s somewhere around 100k–200k in total across different places (even tho the person who first posted it ended up deleting the video). There teachers found out it was us. His friends and family apparently saw it too.
I’m one of the students who helped get the video out, so the school obviously knows I’m involved.
Yesterday shit got interesting.
The principal and coordinator called me into an office with four other students who were also involved, they called out parents and tried pressuring us saying they will harm our educational records, expel us, I asked if i could record the conversation in the office but instead they took my phone. Both of them were basically yelling at us and trying to make me out to be the main villain for “destroying the teacher’s reputation infront of friends and family.” They were clearly trying to manipulate us by saying it was illegal to film that video(it’s legal to film in a public place, but that is hard to explain to your parents)
The concerning part was that the teacher himself told the principal that he has “personal problems” with me and will take “personal revenge”.
Then I was told:
“You’re suspended for 15 days and you will be expelled if you don’t delete the video”, how can i delete a video that isn’t uploaded from my account, and isn’t this blackmail?

They also said things about my character certificate and institutional affiliation, basically implying they could destroy those too.
And apparently I’m supposed to just accept it because “you can’t do anything.”
I contacted 1098 myself after this. They said they would need to talk to the school and both sides and may send someone to meet us. So there might be an actual inquiry/meeting.
Now here’s where I’m confused.
I obviously don’t want to be stupid and turn this into some huge personal war with the school. But at the same time, I’m not going to sit at home for 15 days just because someone verbally announced that I’m suspended.

Can a private school just verbally suspend a Grade 12 student for 15 days like this?
Does it have to be written somewhere?
Can they actually mess with your character certificate because they don’t like what you did?
And strategically, what would you do here?
Do I just let 1098 handle it?
Do I ask the school to put everything in writing first?
Do I go to the local education authority if they refuse?
Or am I being an idiot and should just take the 15 days and move on?
I’m asking what the smartest move from here is.
Ps: i asked him to just say sorry to the student, but he said he would rather resign then do that. He also apparently went to class today and told that, he has “outside connections” and could settle it, implying using gundas but I doubt he would do that, but what kind of teacher would say that to a class full of students