Our Zumba Instructor and her nightmare

So at Zumba the other night just before the class started she said she had something to share with us about her friend who also happens to be one of the Instructors at the gym so so we're all familiar with her, to protect her privacy I'll call her "Our Alternate Instructor".  The unfortunate news was that "our Alternate Instructor" had been a victim of domestic violence.  She continued to say that although it seemed that she was now over the worst she was in need of a lot of emotional support.  Needless to say this was heartbreaking news and affected some women in the class more than others not sure if maybe from past experiences I don't know that's just my guess.
Anyway, hearing this was a shocker for me, I was dumbfounded, it was so hard for me to grasp and process.   It was disturbing and I kept thinking Why? and how bad was she hurt?   Can you imagine the fear she must have been experiencing during the horror of this attack? "Our Alternate Instructor" does have a young son but luckily he was not a witness to this nightmare.
I remember doing some research in college on the statistics of Domestic Violence and one of the facts I've always remembered learning was that we all know or come across someone that is in an abusive relationship but we just don't know it.  Frightening!!  This has prompted me to do a little research on Domestic Violence in this country and I'll post my findings for you on a later post.
Fortunately "Our Alternate Instructor" has recuperated enough to go back to work, with the emotional support of her friends and family I'm hopeful she can start the healing process. Do you know or have any statistics on this issue?  How much do you know about Domestic Violence?  Please let me know.