Alright...

My stepfather was verbally, emotionally, and physically abused as a child. He has not laid a hand on my sisters but has made it very clear he wants to.

Some things I have noticed are:
-he plays favorites. It's not just "This one isn't acting up," it's, "I'm just going to stick my head in the sand over this for you--but you'll get it." When I lived at home, I was the one who was the favorite and I felt guilty for it. Now it's the middle sister, and she takes advantage of it. Sometimes he turns it around and does "mass punishment" and makes the "favorite" resent the "troublemaker".

- He constantly mocks my sisters, if they complain about anything...and even when they aren't, and tries to excuse it as a joke.

-He is excessively clingy towards my mother, to the point that he used to keep us away from her. I mean puppy-dogging her, constantly calling or texting when he gets a minute, that kind of thing. If she leaves the house, he calls her as soon as he thinks she should be heading home, and every five minutes after. When our mother did not have custody of us, he would make excuses about why they didn't have enough gas money to come get us or feed us, and then buy something for himself. He even admitted to being jealous of us.

- He consistently uses a condescending tone, unless he is talking to someone other than us children or my mother. It is not only obnoxious, but it has reached the point that I'm just plain sick of it.

-This all disappears the second another adult is around. I'm just tired of it and tired of seeing my sisters hurting because of this.

I understand parenting, but the second someone so much as asks a question, they're told, "Stahhhhpp, " and then the second they seem upset, they start losing everything.

He can be relatively normal until my mother walks in, and then the animosity doubles until at least two of us are arguing and someone is yelling to cut it out. I don't even live at home--this is what I've witnessed in two weeks just being home on vacation.

This comes across to me as emotional abuse, but there's more and that is part of the reason that I am not only concerned for my siblings, but for him as well.

There are times when he is not clingy towards my mother. During these times, he is usually talking to someone else--cheating. It's like he's not getting enough attention (which of course can happen when you have two children and a busy schedule ) and runs off to find it. It has happened three times in the past few years, and it's terrible. He will completely ignore my sisters and stay in his and my mothers room for hours alone.

I'm just tired. No one is truly happy at home and I think that--while we could all benefit with a little group therapy--that it might be best to bring it up to him first, and have him start going on his own to begin.

How can I gently bring this up to him? I want to talk it over with my mother first so I know I'm not completely skewed overhead, but I want to kind of be the one to tell him . I think our family would be a lot happier.