How do you help someone who has been slowly manipulated in a marriage for many years open their eyes and see that their wife is the issue?

Just wanted to respond to some of the comments because I'm not allowed to respond to individual people. This is not misconstrued as manipulation it is manipulation and it's not me getting involved in other people's relationships. Being that we are such a tight-knit family everyone sees everyone constantly so is kind of like it's my family. And it's not okay for this relationship to continue while the sister-in-law person involved is putting a strain on her kids relationships with her on her mother-in-law's relationships with her on my relationships with her on her fiance's relationships with her and her husband's relationships with her. He loves her and he's blind to the fact that she's doing this to him and to the family. It's been slowly happening and now other people are realizing it and it's not okay for it to continue. The husband won't do anything because he's at her bedroom call she says jump he says how high. There are other people that are not as close in the family but know this person and realize that yes she is an issue and yes something should have been done a long time ago but my fiance isn't going to say anything because he doesn't want to hurt his brother and my mother-in-law won't say anything because that's her son and she would feel bad if he loves someone and she were the cause of ruining the relationship. in my opinion I think the relationship should have been ruined because it's not okay to let someone do this and for my fiance mother-in-law not to speak up because if you really care for your son and brother you would say this is not right for you We don't want this in the family. I do understand her ways I do understand her actions I do understand that it is manipulating I am a behavioral therapist so I'm aware of everything I just can't make a big enough difference to change the minds of the people involved. I think the divorce is absolutely warranted and needed because it would save the family it would make the family happier Yes there are kids involved but that doesn't stop the fact that she's a horrible person Life through her teeth pretends to be nice but it's really backstabbing and won't listen to anyone It's her where the highway I think this way I act this way if you don't act or think like me you're automatically wrong and I automatically don't like you but I'll pretend I do.I'll put in a big show and cost fights when there are family gatherings so I can have witnesses as if the witnesses are going to adopt her up or stand up for her or something like that.she's a person that pretends to know everything when someone proves her wrong and tries to tell her something else doesn't matter I'm right even if I'm wrong.

You know, it's bad Karma to try to destroy someone else's relationship just to save your own. If your fiancé was truly devoted to you it wouldn't matter what's going on (in this cryptic screed of yours that appears to be about other people and therefore is none of your business). 

This man lives with his wife. You think he's never noticed that she's controlling and manipulating! He knows it. For this woman to be putting a strain on your relationship with your fiance is about YOU and your fiance! People have only the power over you that you allow them. It's likely that no one needs you to open their eyes or tell them what they should think or feel. Enough of that going on already. Don't gossip, don't spread gossip. That would likely be the most helpful thing. 

this man is a beta and unfortunately not all can be saved .... or want to be saved. 

The pattern of your "questions" is concerning.  Any reason you are SO very involved with other people's relationships?  No relationship of your own?

STAY OUT OF IT AND MIND YOUR OWN BUSINESS - AGAIN.

I'm sure he knows it a lot more than you think, but he has to live with her, you don't.  In my experience the only true way out of these situations is divorce and that's not something he may want to do.  Otherwise like others have said it's hard to give concrete advise without addressing the very specific details of each incident. 

Nothing like a non-specific question.  But what it sounds like is that you have discovered the definition of a successful marriage, but misconstrue it at manipulation or cluelessness.  There is an old saying that should explain it definitively ... "Happy wife, happy life."

You don't. But maybe, just MAYBE you could stop coming here and endlessly whining about it. 

You cannot help.  If it is someone else's marriage other than your own, NOTHING you say or do will help that person.  It will only cause resentment toward you.