My partners and I all know about one another's partners, but we share different amounts of information about them. One of my boyfriend's can enjoy hearing stories about my husband; the other can't. I don't think it's because he wishes I wasn't poly, it just doesn't make him feel good to hear those details. It may not be rational, but nobody is always rational, and that's okay. You don't need to make a big deal out of it. You can just say that you'd rather not hear about this person. It may not make sense, but it's how you feel and it's easy to accommodate.
As far as your general guidelines go, I'd try tweaking things a little at a time so you can see how it works for you instead of making a drastic change in one go. A few months to test the waters should not be that significant in solving this long term issue. Perhaps let your partner know you're not sure about the best way to handle information sharing going forward, and ask of she'd be willing to do some trial and error woth you to try to find something that works better for both of you.