I need advice about a family situation

Please forgive me if this is not the right forum to put this. I just need to get some advice and get some of this out.

I am very troubled about a family who lives near us and have been friends with for about 10 years. I am troubled because of what I have been told, recently by my 17 year old son, Greg, who is good friends with the daughter, Sasha from this family I am referring to. (Btw, I changed the names of everyone just for the sake of everyone's privacy)
Greg's and Sasha's relationship has been like brother and sister ever since they met. There has never been any romance, but a close friendship over the years. They have been able to confide in one another, which I think is wonderful. Greg and I are also pretty close.
Greg has recently told me that Sasha's mother, Mollie is emotionally and verbally abusive to Sasha. Mollie, according to what I have been told by Greg, has basically repeatedly told Sasha that she is a "slut", and that she has ruined her life and that she hates her. And, Sasha tells Greg that her mother forces her to be an over-achiever, so much so, that she has very little free time. I can attest to the fact that Sasha seems to be an over-achiever, and there's nothing wrong with that, but until fairly recently, I thought that the over-achieving was mostly because that was what Sasha wanted, and not because her mother was forcing her to do all of these things. Personally, I don't have a problem with parents pushing their kids to do more than they might want to do. I find nothing wrong with making a child take music lessons, or join Girl Scouts, or volunteer, or get better grades. But what I have learned recently, is that Sasha's mother is quite excessive in forcing Sasha to over-achieve. And what is even more odd, to me, is that whenever I talk to Sasha's mother, she is always telling me that it is Sasha who wants to do all of these extra things, and not the other way around. Mollie will tell me that she has to force Sasha to take a night off from all of the extra stuff she wants to do. But what I am hearing from Sasha (through Greg) is that this is absolutely not the case, and that she cannot wait to graduate and leave home to get away from her overbearing mother.
I am so puzzled by this bizarre relationship. And, I am also puzzled at how Mollie interacts with me and my family. She seems to genuinely care about our family, yet if what Sasha says is true, Mollie outright lies to my face about her true feelings about our family. According to Sasha, Mollie thinks we are lazy and too permissive with our children. Mollie will drop by from time to time to chat or catch up, and she acts like she is genuinely interested in our family. She will ask lots of questions about how the kids are doing and how I am doing. On the most recent visit, she wanted to know how Greg was doing(who has been hospital homebound for school due to a medical issue). Mollie said that she wanted to know if there was anything her family could do to help us through this tough time and if Greg would like to see Sasha and hang out. Yet, while she was sitting and chatting with us, she apparently sent a text message to her daughter saying to ignore any texts or phone calls from Greg. Greg told me that Sasha was able to show him the text that her mom sent her while she was here.
I can handle it if someone doesn't like me or my family. If someone has issues with me, then that is fine. But this woman has been apparently a big liar over the years to me and my family. She seems to want to put up a big facade for us to see. I don't understand the need to keep up a friendship if you fundamentally don't agree with the lifestyle of another person. I wonder if it's all about looking like something you're not, to try to impress someone, like a big ego trip.
But what I have the most trouble with is Mollie's relationship with her daughter. With all the troubling reports of teenage suicide in the news these days, I worry about Sasha's emotional wellbeing. Sasha has always seemed like a sweetheart. She is really a great young lady whom I wish the very best and I would be proud to call her my daughter. But after hearing about the emotional and verbal abuse that seems to be going on, I am very concerned. And while it does worry me that Mollie is pushing her daughter too hard to over-achieve (believe me, if you knew all of the things Mollie has been forcing Sasha to do in her spare time, you would understand that there seems to be something to be concerned about), my primary concern is the verbal abuse. I asked Greg whether Sasha had ever tried to go to a school guidance counselor to talk about it, and he said that she didn't feel safe doing that. She said that the trouble with that is that the guidance counselors are duty bound to call the parents whenever there was a problem in the family, so Sasha would not feel safe to have that kind of conversation with them. I also don't want to break the level of confidentiality that Sasha and my son seem to share. I love that they can talk to each other and talk about what they are going through. I don't think that Sasha would feel safe with talking with me about any of this. I would love to be able to talk to her in confidence, but I don't think Sasha would feel comfortable with it. I have also been told that there had been physical abuse by the mother, but that seemed to have stopped. There was one account of Mollie threatening Sasha with a knife. That apparently happened several years ago. But I know that emotional and verbal abuse can often be more painful to go through than physical abuse, and have deep and lasting effects on someone's psyche. FYI, I did call the D.C.F. anonymously, two years ago, because I had heard from my son that there seemed to be an abusive situation going on there. I was told that someone from D.C.F. would go pay a visit to the family to investigate. I thought at the time that this did seem to help with the abuse, and maybe that is why the physical abuse seems to have stopped. I was very hopeful that things would get better, and maybe they did for a little while. Maybe I need to make another phone call to D.C.F.
So, has anyone here ever been through a similar situation where you suspected abusive relationships? I'm not sure what, if anything I can do to help, but I would really like to. Sorry for the long post. It's such a complicated situation. Any advice would be appreciated.