My best friend's ex-boyfriend?

He follows her around, has texted her that she's a "Stupid f***ing sl*t," and then begged for her forgiveness. He threatened to kill himself, and he said "I hope you end up dead in a gutter and no one comes to your funeral!" He says "loves" her still, but he's a creep who threatened to give her roofies. She wants to stay friends, but she won't listen to me! He's a creep, with a psycho side! I've told my mom, who told his best friend's mom. I'm worried about the safety of my friend! Please, please help!