I have been involved with someone for 3.5 years, and whenever I urge him to seek DBT therapy, he turns against me, and blames and projects and insults me. For example I didn't speak to him for three days, and then I called him after work he answered the phone in public and said "you're a psycho!" Sometimes when he splits and goes into his emergency functioning he will suddenly threaten to call 911. He finally did the other night when we were having fun, though nothing happened and the police believed me when I said he was undiagnosed borderline and that we were on the roof and he wanted me to climb a dangerous ladder with him. Though his behavior is not new, I feel that he is a danger to himself and others and especially me, and I finally feel ready to step back from a dangerous person and do not want to see him unless he enters into therapies.
Are you married? Unfortunately, we all learn that when someone is a "danger to themselves or others", we should probably call 9-1-1. Not sure how much authority you'd have if you're just dating though.