You shouldn't base anything on what the forum says, tbh.
He's a fucking horrible person and you shouldn't have to have him in your home, but, before you do anything, (and this is coming from someone who's trained in DV/worked in shelters for years...) contact your local agency, educate yourself first, on supporting her.
Shit is gonna get rough. She may not make the "right" decision at first, or at all. She's hormonal, in love, thinking about the baby, and blinded by his bullshit (as y'all know, I've been there...) fear will make you do some dumb shit. You need to be there for her, but not judgy, set boundaries, but be flexible for change. It's gonna be a crazy ride.