Mother living with BPD

I need your advice and support. My beautiful, empathic and charasmatic son wa initially diagnosed with Anxiety and Depression. He has been able to maintain his emeotions until recently. His has been unofficially diagnosed by skilled professionals as having BPD traits. In the past month. my son'd behaviour has esculated to include violence to property, unexplained rage towards us as his parent s and his siblings, stealing and an unxplained loyalty to new friends who are not from his long term friend ship groups... troubled kids who support a seperation from his stable and loving - but quite frankly over protective family ( 3 years trying to keep him engaged, not self harming and alive). We have not shared the possible diagnosis, struggle to deal with his rage and abborant behavior but love him unconditionally. His girlfriend is abusive and anyi family... how do we endure, show our love and how much do we disclose to our 18 year old who has not been abondened, neglected or abused?