No, it's not too much to ask. I was in sort of a similar situation about a year and a half ago. My ex never actually cheated on me, but he sure humiliated me. I'm not really the jealous type, and there were a lot of girls he was friends with and could go hang out alone with, because they weren't trifling heifers. But this one girl was always flirting with him, right in front of me, no shame, and talked badly about me to people I knew. Saying how much of a bitch I had to be, and how she'd be better for Dan, etc. And that was fine as long as he was still on my side. But he started blowing me off to hang out with her. It got to the point where people were asking me if anything was going on between the two of them. That was humiliating. And I got upset about it. But he'd defend her to me and put me in a really awkward position. That, combined with several other issues, eventually broke us up.

So... if this guy is smart, he'll tackle this situation with kid gloves and respect your boundaries with this ONE girl. You seem very understanding about things most girls would get uptight about (including me, for some of those ). It's not hard to not hang out with someone alone. And the whores line was way out of line, haha, wtf.