Hi jwanh,
Setting boundaries with a loved one who has none is an act of love.
Lacking any boundaries (a key problem for someone with BPD) means that we have to create them. When he dysregulates and becomes abusive, he may eventually tip into a tender cycle and feel bad about feeling bad, a downward spiral.
Protecting yourself (setting boundaries) is a way to prevent him from feeling worse about himself.
There are
success stories here. And there is a book called Beyond Borderline that includes stories of BPD sufferers currently in some stage of treatment, who consider themselves to be living lives worth living.
It takes tremendous strength to not be emotionally injured in a BPD relationship. You have to put yourself first, and that can be difficult and counter-intuitive. You have to set boundaries (and use communication skills like validation) out of love and be willing to step into what can often feel like a parent role.
It's not easy. You need support.
We're here to walk with you.
LnL