Allright, I didn't want to do this, because an argument with you seems kinda pointless, but I have to address a few things.
First of all, you're way off the mark on many things, and I don't know that if your style is something that is supposed to be funny, or you just have serious problems up in your head, but reading your comments in the thread, seriously indicates the latter. If that is the case, get some professional help like yesterday.
Secondly, it's clear that you have either 0 knack for psychology, or life in general, but there are problems in life, that should be addressed, regardless of how painful it is. Not everything should be buried under the sand, and sometimes, people need an outside force to push them, to face said problems. This is one of those cases. Saying that she already moved on is false. Haley still bears the cross of the events, mostly because of the resentment from her mother that is still there because of this whole case. Even his dad has some issues with it judged by the talk he had with the MC during the second visit, he just seems a bit more subtle, and probably doesn't need the feel to pressure since his wife takes care of that. The fact that the Mom is still bitter about this after years, without ever getting the whole picture and just accepting Haley's typical victim self blaming behaviour is a huge mistake from her part, but it doesn't make it right. It's like in medicine, when a bone breaks and doesn't joins properly, they have to break it again in order to let it heal. Also with the last update, Haley herself admits that Klaus hurt her, which pretty much settles in stone as of who is right or wrong in the debate of should this be addressed or not.
Thirdly, as for the MC should take matters into his own hands or not. Victor during the dinner suggested something similar when he mentioned that he "has some connections" or "knows certain people", that should be contacted after a while. I don't know how you'd react if someone close to you or love gets hurt in a similar way, I guess you'd be pissed off as well, and would want to settle this yourself. That's the normal human reaction to a situation like this, not some 13 year old's revenge fantasy. You don't have to go to far extremes, or be a self proclaimed hero of justice, and yet want to deal with something like this is. You can also remain smart about it yet effective, it is not an unaccomplishable feat.
Of course, there are other ways to deal with this, or even combining them, in this day and age especially, depending on the situation, as I mentioned it a few pages ago, but shit like this shouldn't be simply ignored anyway. I mean, thinking otherwise is your prerogative, but that makes you either someone that lacks empathy towards to your supposedly loved one, or a spineless coward. Both is fine, but the fact that you're judgemental of others that thinks or feel otherwise and even try to mock them is just ridiculous, period.
To be honest, I wanted to avoid to take this into a personal level or write a long ass something in turn, but with the replies you made not only for me but for the others, you pretty much asked for it. I don't know why you got on your high horse, but get off from it really fast, or you're gonna have a lot of problems in real life dealing with people that takes none of your shit.