I have no idea what I should do

(Warning: pretty long)
So basically, there's this this guy who I'm not friends with; I don't particularly like him since he's rude and a bit gross and we aren't close, we just kinda have the same friend group (though I don't think most of them like him either).

So this guy, - Let's call him Kian - had this mini mental breakdown a few months back, after school. The reason for this was because school was threatening to call his mother and exclude him because he had gotten into a fight ( It wasn't a serious fight or anything, just guys fake fighting, but some parent drove past and reported it to the school). So he was having this little breakdown, crying and everything. And me and my friends were just kinda laughing at him ( I know it sounds like we're jerks or something, but this Kian person is literally not a good person) we thought he was just kinda overreacting since we didn't think the school would take it all that serious (and they didn't, they never ended up calling his mother or excluding him,, he didn't even get a detention). But while he was having this breakdown, we were trying to calm him down by saying it wasn't that bad but then he confessed something to us.

He was like, "You guys don't understand, my mum isn't that nice. One time I was just having a bath, and she came in and tried to drown me."

Now obviously everyone was kinda shocked, he literally confessed that his mother tried to kill him ???
Now let me say again, this Kian person is an asshole. Unlikeable personality, unlikable in general. But I did feel bad when he said that.

So that's incident one, happened a few months ago.

Now back to the a few weeks ago, I still don't like this Kian person. in fact I don't know anyone that does (Like I said, he's very unlikeable). The whole "mum tried to drown me" situation was kinda turned into a joke between the people that were there when it happened and only like 2 people outside of the people that saw it knew about it. He seemed better and didn't like talking about what happened.

Now a few weeks ago, a few guys that didn't like him decided to jump him before school. One of these guys, lets call him Noah, especially didn't like him. They all jumped him, but it was supposedly all a joke and they were laughing about it (including Kian). But soon later it was reported to the school and the people involved were all excluded - despite it not looking all that serious. Kian swore that he never snitched, but Noah didn't believe it. So they've kinda had an even worse relationship since then.

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finally, now onto my actual question. that was all just some context lol.

This happened today. Noah's still pissed about getting excluded. So today he decided to tell a teacher at my school about the situation with Kian's mother (despite him not being there while he was crying, someone had told him) he told a teacher, and wrote down the names of all the people that he knew were there that day. Including mine.

He came up to me to me and told me that I better tell the truth or else the teachers would think he was just lying and he would get into trouble, so here's my problem.

He's not lying at all. And I know that because I was there and heard everything Kian said. But, I feel really bad. This is pretty serious and I'm pretty sure he could get taken away from his mother since he's not legally an adult yet. I've talked to some of my friends who were mentioned, and some of them really hate Kian and don't mind telling while others say they're just going to pretend they didn't hear anything, but I feel very uncomfortable about it. I don't like Kian either, but I don't want to bait him out and hurt his family. But I'm also not sure if I should lie. Kian doesn't know that Noah has told a teacher but he'll probably find out soon enough. I really hate being put in the middle of this, I have no idea what I should do.

What would you do?