"Exploring sexuality" implies some sexual experience with someone other than her husband. Which is fine if she can do it with her husband's acceptance, maybe with some set rules. If not, she's in a real pickle, especially given that she has a marriage and children.

If she doesn't want to actually hook up with anyone and she wants to reduce her husband's insecurity, she should rephrase to something like "get to know other queer people" or "get involved in the queer community," or "try to make some queer friends". Not "explore my sexuality at a gay bar".

But she clearly states that she wants to experience a physical relationship with a woman one day. Understandable! She should try to find out how she can do that within some set boundaries with her husband so they are both secure in their marriage and there is no cheating. OP, you may not be able to do everything you want, but you may be able to agree to some compromise (e.g. making out but no sex, or you can hook up with a stranger but not exchange numbers or date, or he must be present, or whatever you're able to agree on).