Hi Eggshellz
*Welcome*
In my experience, it's best not to acknowledge that you are aware of their disorder.
If you are familiar with BPD, you are aware that they are emotionally incapacitated. So they do not think like adults - in an emotional capacity.
If you are made aware of an illness or disorder, you'll probably take steps to rectify it immediately.
An emotionally incapacitated doesn't necessarily have this level of understanding, instead, they may feel it is shameful to them, or even an attack.
You indicated that your husband has rage episodes.
I would strongly advise you not to inform him yourself, as this may result in highly unpredictable and potentially dangerous behaviour
I hope you will find this article helpful:
https://bpdfamily.com/content/how-to-get-borderline-into-therapy