"Violence is not a solution" - Bullshit. It is. Mc gets Klaus somewhere, crushes his junk, problem solved. As far as the jail thing goes, Klaus would have to lose just as much or even more if things go to court. Remember "Me too?" Haley probably wasn't the first and the last of his victim, and in a situation like this, you only need one case to lit everything on fire. So it is a viable solution.
Victor suggested even something similar or further than that. As for why he would help him if the Sandra path is over? The two doesn't depends on each other. Victor was hitting off well with the MC even before Sandra, and now has a kinship with him as both of them are being in a similar situation. Also Victor is an adult, and doesn't seem like a petty one, to turn away from something like this just because the kids broke up.
As for the forgiveness of Haley, yeah, she probably won't totally forgive this for a while completely, but at this point, taken the Haley route, their relationship seems to be stronger, than this ruining it completely.
Tbf, I don't really enjoy the whole Klaus twist, I'd rather seen things continue without this, but because it's the best erotic vn-s I met so far, I take it as it is, and hope something good comes out of this as well at the very end.