Yeah, it's always touchy asking someone not to communicate with someone else. I can understand why you wouldn't want the public slander on his page, but to be honest, people see that kind of thing as more a reflection of the speaker than the subject. I honestly don't blame your boyfriend for taking offense at the request.
If you want to avoid her drama, my advice to you regarding the Facebook issue is to block her from your own Facebook so you won't have to see her posts on your husband's wall. Now that's not what I would do personally, because I always like to keep an eye on my enemies. But I'm really good at ignoring stupid people and not allowing their drama to affect my life.
I think you can also report inappropriate posts? Not sure though...
Gralson: my husband. Auto: my girlfriend.
Zoffee: Auto's husband. Cue: Zoffee's boyfriend. Bookie: Cue's wife.
"Crowns do queer things to the heads beneath them."