Do it. You can get your friend to back you up. You can probably get help from other colleagues (im speculating).
Go to the police and tell them the situation. Tell them you wanted to work in peace and you were hit or something, you know the situation better.
And if it comes to a "draw" and nothing gets done, the cops know, the others dont have proof too and you will forget that job and either get another one or go back to boxing. And carry a knife or something with you in the near future, if they decide to hit you on the street and bring weapons you have something to fight too if you need.
This is just me speculating but it's up to you in the end. If I could I would go there back u up even if we dont know each other.
I think I'm just gonna let it go. I'm 19y old, future ahead of me, this nigga and his colleagues been working there for years, they're done with life. Fuck them.
I am going back this friday to challenge him and laugh at him and his colleagues, but I ain't gonna beat him up or whatever anymore.
The plan with my friend going there to get him fired is still on, though. lol
Thanks for the support btw everyone, really great of you all.