Try making a clear list of what behaviors that she exhibits that are dangerous (whether it be physically, emotionally, etc).
List the worst one first
I'll start with where I was at last January (2013):
1. Physically abuse (rare but serious)
2. Has threatened for serious harm to come to me
3. Has hurt our dogs
4. Threatens our dogs or to get rid of our dogs
5. Verbally abusive (things like telling me that I should have never been born)
6. Calls me names
7.  :)amages our property
8. Attempts to tell me what I believe
9.  :)ominates my time even while I am at work
10. Exposes our son to conflict
11. Swears in front of our son
12. Attempts to limit my interaction with friends/ family
13. Assigns blame for the things going wrong in his life onto me.
1-4 were rare behaviors... .so I actually started on #5 and here is the post where I was given guidance initially on boundaries.
https://bpdfamily.com/message_board/index.php?topic=200881.msg12251290#msg12251290It was absolute hell but from about April until Sept I fought hard to stand up for myself - I got beat up, I ended up in a DV shelter for a week, I called the police on my husband but I decided that I was going to work really, really hard to stand up for what is right and to love him throughout the process regardless of how he acted. I became at peace with the fact that I may lose my marriage in all of this, but I was losing it anyway.
Today here is where I am at:
1. Physically abuse (rare but serious)
2. Has threatened for serious harm to come to me
3. Has hurt our dogs
4. Threatens our dogs or to get rid of our dogs
5. Verbally abusive (things like telling me that I should have never been born)6. Calls me names Still moving off the list but very rare
7.  :)amages our property Still moving off the list but very rare
8. Attempts to tell me what I believe9.  :)ominates my time even while I am at work10. Exposes our son to conflict -
Lessening but I am still working on this.11. Swears in front of our son
12. Attempts to limit my interaction with friends/ family -
Lessening but I am still working on this.13. Assigns blame for the things going wrong in his life onto me. -
Lessening but I am still working on this.What changed for me was that I realized that I could not continue to expose my son to my husband's behavior and if he wasn't going to act like an adult, then I was going to be the one in charge. So far the result has been good.
I can actually go back through and almost give you the date when each of these behaviors fell off the 'acceptable list.' It was a result of firm boundary enforcement. I'm glad that you are not afraid to call the police, but they should be the measure of last resort when everything else has not worked.
I didn't realize how damaging my husband's bad behavior was (is) to my son until I really started working on the issues.
What does your list look like?