<human>: My good friend [31F] and I are in an outdoors club (hiking, boating, that sort of thing) together. Last year, she was the other woman in an affair. Because I'm her good friend, she would tell me all about it. I tried to convince her that she probably shouldn't get involved in infidelity, but in the end, it's her life and her choices to make. She would tell me how her guy really didn't want to be in the relationship with his crazy, batshit girlfriend, and was just playing for time (of course). The affair lasted about a year.

Since then, "crazy, batshit insane girlfriend" has not only joined our club, but taken a leadership position, and is not as crazy and batshit as advertised. In fact, she's really sweet and *loves* my friend and is trying to be friends with her. Awkward. But even more awkward is that she is in fact good-natured, smart, and independent, and I'd like to be her friend myself (I don't want to date her or anything; I have a relationship of my own that is doing just fine).

But now through really no fault of my own I have this big secret that at first had nothing to do with me. Now it has something to do with me. Telling her the secret would destroy the club at this point, and I don't really want to anyway, since it's not my place. But it seems she's likely to find out somehow, from someone, at some point, at which point it will be clear that I knew the whole time.

I want to be her friend, though, and want to see the club survive this. What would you do?

Give me the gist of the text in a nutshell
<bot>: Batshit GF of friend's affair partner is not so batshit after all, we're becoming friends, but she will eventually find out about the affair, and that I knew about it. What to do?