Dear wideawake
I am sorry you had to listen to your sister-inlaw... . she is obviously uneducated on the topic of BPD and has her own issues. That is not the kind of support you need right now.
You need tools to deal with the raging and the violence etc... .
Have you read any of the links here? First in foremost you need to change the way you interact with your daughter. If you decide your boundary is that she will speak to you with respect then stick with that... . any time she begins a conversation and she is unable to be repectful I would end it right then and there... . walk away and not engage her. Learn how to defuse the rage... . boundaries are very important.
If you feel unsafe in your home you need to make a safe place for you and your husband... . I have a lock on my bedroom door... . the electronic kind that you punch numbers in to open... . this is a place you can go to feel safe... . if you really feel unsafe I would call the police... . I found that only when I started to call for outside help did things change. You do not need to be afraid in your own home.
Here are some links... . I hope they help... .
Video--Validation: Encouraging Peace in a BPD FamilyValidation--Tips and Traps for ParentsTOOLS: S.E.T. - Support, Empathy and TruthCommunication using validation. What it is; how to do itI really found that changing how I interacted with my daughter was key... . setting some boundaries and following up on them... . CALL THE POLICE... . do not be afraid to get the help you need. Ask them for a evaluation if she is totally out of control.
Please take care of yourself... . limit your contact with your SIL... . she doesn't help the situation and doesn't understand... . before my dd16 had a DX of BPD i tried the tough love appraoch and things just got worse... . you really need to approach them in a different way. My dd16 is also ODD and that just makes things extra hard... . everything is a battle and a power struggle.
Is you dd getting any help? Does she have a therapist? Hang in there... . it can and will get better... . we are all running a marathon here not a race... . there are better days ahead