grandchildren

My ex-daughter in law appears to have some sort of anti-social personality disorder, but there's no diagnosis. During the divorce the law guardian wanted to send her for a forensic eval but it didn't happen. She exhibits just about all the characteristics - she can be charming, she is a compulsive liar, manipulates people, has been in trouble with the law (vandalism, fights, stealing) moves every 1 -2 years, never pays her rent (boyfriends pay for a few months, give up and she waits for the eviction notice), has never had a job for more than 9 -10 months, if that, never stays in a relationship for long, filed bankruptcy at 21, will be filing bankruptcy again when she's ready (it's her plan to never pay bills), has put bills in the names of other people, she's very vindictive, she has absolutely no empathy at all. When her older son was sobbing because of th death of one of her boyfriends she ignored him - my son comforted him (and they were in the therapist's office), I could go on. She has two children - 1 is my son's. She hasn't allowed the older child to see his father in 3 years. My son has had visitation on a regular basis with both children for 3 years, but things had taken a turn for the worse recently. She apparently e-mails him, text messages him and calls him constantly, but she won't allow him to see the children now, allow she blames him - he didn't pick them up (she told him he couldn't come over), etc.

I have some concerns and I don't know where to go to find out:

1 - what is the impact on children of living with a woman like this? theya re 5 and 7 1/2. The older boy has moved 10 times since he was born and has had, in addition to his father, 4 "step dads". All of her boyfriends become instant step dads - she has family pictures taken within weeks of starting dating them. He's in 3rd grade and attending his 3rd school.
2 - she gets angry very quickly, she has hit, slapped and punched adults (both men and women), she has vandalised cars (keyed them, threw rocks at them, drove my son's car along a guard rail and scraped it).
How can I tell if she is capable of more violence? of hurting the children? or my son?

Since you as a grandmother have no legal rights/ claims to the children, you must convince your son to take this woman to court for custody, providing witnesses, proof of past violence. If this is impossible, hopefully your grandchildren will be stronger because of the undue adversity they have been made to suffer so early in their lives, and escape from their mother's clutches as soon as capable.

In some states, AZ is one I think, grandparents do have legal rights re: grandkids