How to tell a difficult person you're pregnant

Leisha • I'm excited to know I'm actually going to be a Mommy! Daddys excited, and claims he's having a daughter!
I'm going to have to tell someone who wished me death once, then tries to be friendly yet set me up with her boyfriends brother and completely trashes my man. She's going to have to know sooner or later because I'm excited to finally share our exciting news with Facebook. She's also going to have to know sometime because her son will be a half brother in 6 months. Oh sure, I can wait and tell her a few days after giving birth, but she really wants to go have a few drinks. I hate lying. But I had to because my family didn't know until I was 3 months pregnant, and why should everyone but my family know? Plus, if she wished death on me once, she's going to do it to me and my baby. And if, God PLEASE forbid, my baby doesn't make it, or has serious medical issues, I know better that it's not her, but I will blame her and hate her anyways until I regrow up again. So, when and how do I tell her? Wait until she asks me to go out again or until birth and fake drinking or what? No, I really don't care to be around her much, but I'm weird.