First of all, that's hot. I just wanted to get that out of the way
Your hubby is cool with it so that's a non-issue. Aside from that, this sounds like it's mainly about you coping with homosexual/bi-sexual feelings, which is not a pua-specific topic.
However, I've had some experience with a number of bi-sexual women, and bi-curious ones, so I kind of know what you are going through. As far as approaching your instructor, that's kind of tough, because it's similar to hitting on a person who is at their job. I have no idea what that person's opinion's are about being professional and not hooking up with client's but that could be a problem. So you want to find out their opinion on that before putting too much effort into seducing them.
If I was in your shoes, I'd wait till the end of a session and then when it's wrapping up start asking personal questions and flirting. You need to find out if she's single, if she's bi, and if she is willing to hook up with clients. Good luck, because that's gonna' be difficult I'd imagine.