I think the first step should be identifying WHY you feel disrespected. I mean, if you posted all kinds of stuff about him when he's with you would you expect her to get upset? What would your reaction be if she asked you to change your personal habits?
I agree that not being her friend on facebook seems like more of an option than trying to get her to change. Unless she is breaking a boundary that has been set, I don't see why you should interfere. You don't have to interact on facebook, so just don't. You can also opt to not follow her automatically so that her posts don't come up on your newsfeed. You can still go to her profile when you feel like it and interact as usual, but you don't get the "in your face"ness of constant posts. I've done that to a few people who I find irritating with over-posting.
Does your boyfriend think she does it with malicious intent? I would think he would know her better than you do and would put a stop to anything she does to purposefully try to hurt you. A lot of people just post a ton on FB. Unless you have reason to believe she's doing it to hurt you, I would find a way to deal with it (by blocking her posts on FB, unfriending her on FB, or whatever). If you DO have reason to believe she's doing it purposefully to hurt/bother you, then you definitely should talk to her about it.
It sounds like you're a bit insecure, and while in general you don't mind the poly nature of your relationship you don't like having it right in front of you. I wouldn't necessary say there is anything wrong with that, but I don't think it gives you the right to ask her to do something she obviously enjoys unless it is causing you damage.