Family & Friends

How do I stop my friend from getting into a fight?

Quick backstory, So we were all a group of friends from school (like 10 people), and 2 of the guys (We'll call them M and T) were extremely close or at least looked like it until they both really and I mean REALLY liked the same girl, M started calling that girl a whore in front of everyone for some reason and T didn't react directly to it but looked like he wanted to kill him and went ahead and told the girl about it, I won't ramble too much, but it ended with M lying to the girl and her believing him (and everyone else in the group because they all hated her, I didn't get involved at all) when saying that T just wants to fuck her and he's talking to other girls and that he lied that M said that (even though he did)

Now T was away for a year, but now he's back, I just saw him and he told me that he has unfinished business and he knows where M will be tonight and stuff like "no one knows him like I do, I know exactly how trashy he is, I'm gonna wreck his life", it was really intense, is he right to want to do this or should I find a way to stop him? (I'm also afraid M will be with his friends and then T will get hurt if it's like 5 on 1)
Updates
+1 y
I'm asking here because all of my friends are friends with M and think T is an asshole, while mom told me that it's none of my business and "that boy always looked for trouble"
How do I stop my friend from getting into a fight?
Post Opinion