I’m an old poster who hasn’t been here in a long time, but I pop by occasionally to read. (Divorced, NC with anything bonkers and well now)

But I wanted to chip in on this issue, Ginger.

I am very sorry, first of all, that your xh has done this and for how distressing it is for you and little G. I am sorry that it is causing you even a moment of angst let alone sleepless nights. It’s amazing - and not in a good way - how some kinds of humans can create such chaos and disorder around them, isn’t it?

Seems to me that the No 1 priority is little G’s wellbeing and that this is the only thing you are responsible for. Wise of you to see that a third party IC might help her unpick what she wants to do and what is acceptable to her or not wrt to what she now knows about her father’s behaviour. And what a great job you have done with little G and the kind of relationship you have, Ginger, that she could tell you.

As I understood it, little G seems to have two main issues.....that she does not want to spend time with him/them carrying this important secret or feel responsible for what happens....and that she fears that her father will reject her when/if she tells him she knows. Is that right? Understandably, she may have some other feelings too about what kind of man her father is, about her stepmother’s feelings, about what he did all those years ago to you and her....those might take a bit of time to process ideally with support from a good IC and you....but the pressing big issue for her is carrying this secret bomb and how her father is going to react when/if she tells the truth?

This patch of my own life experience taught me, I think, two big lessons. The first is that being gaslit, by others or ourselves, is a terribly damaging insidious thing. The second is that agency matters and feeling that others support and validate our right to pin down what we need and act on it matters.

So it seems to me that the first step is to help little G put words to what is ok and not ok for her right now, to work out what her boundary is wrt to her father now she has facts that she did not have before. And you are the kind of parent who is well able to do that which is a blessing for little G.

Doing that though probably does mean being VERY clear in your own mind about what lives on your side of the street (and hers) and what does not. I know that over the years you have stepped up to have some kind of active extended family relationship with your xh and his wife believing this was best for your daughter. However, imho this leaves you more exposed to getting pulled into a bit of a dysfunctional triangle with put bluntly a couple of humans who harmed you and at best don’t share your values. Xh did what he did to you and very little G. And his wife, as an ow, was ok with having an affair with a man with a pregnant wife and/or small child. And those actions created a lot of tough practical consequences for you, Ginger, a harder life for you and little G than you might have wished. I’m not talking about any spirit of revenge, let me be clear, but I am saying that from the cheap seats the karmic mess of their relationship is absolutely not your job and it seems a bit skewed that you might even consider stepping into it even in a small way. Imho it’s not your responsibility, not your side of the street and not healthy for you or little G to even spend any mental headspace on it.

So again jmo but I think you should put aside any of those ‘owife has a right to know’ or ‘if I were her....’ thoughts. They may be true, but it’s not your job. Owife cheated with a man who cheats and betrays trust even with a small child in the mix; she got a husband who cheats. That is her life lesson to figure out and you owe her less than nothing.

So, lay down some of those moving parts, Ginger. They exist but they don’t belong to you.

Put simply, it seems likely that little G is going to want to say something to her father along the lines of I know x bc I saw why, i’m not comfortable with carrying this secret and spending time with you/owife and so, for the moment, I am not going to spend time with either of you. You can explain that to owife however you choose, the truth or not, but I am staying out of this mess. Full stop. Like you, I absolutely expect that your xh will react as cheaters do....that he will gaslight her, attack her, deny it or try to make her feel guilty or responsible.....which is why little G should not have that conversation face to face with him without support from you (if you feel able to be calm and objective) or an IC. Or why it might be better for her to communicate her boundary in writing.
And then both of you will need to stay out of the sandpit of the disordered when, entirely predictably, him or owife try to pull you into that particular triangle lol. So, you are probably going to need a new boundary with them too, Ginger.

It is horrible. But it isn’t as complicated as it feels, just deeply unpleasant. Little G knows a secret that has the potential to cause a lot of damage. But it isn’t her secret and she has good instincts that she doesn’t want to own it, that she wants to detach from it....ha ha, a DB child, great healthy survival instincts! Which means detaching from him and owife bc that is where the secret lives. At least for a while.

Your job is, as I see it, to help her figure out her boundary for herself and to find as straightforward and safe a way as possible to communicate it. Then to keep you and her, as far as you are able, away from any potential triangulation....let the cards fall where they may wrt to your xh and his wife and his wife’s best friend. (Good lord, it sounds like one of those Italian classic farces doesn’t it?) while you and little G focus on nice clean lovely things that are not mired in the BS of someone else’s farm. And that will also give little G a bit of time to process how she feels about the kind of man her father is in light of this new information.

Jmo, of course.
But I hope that I have made some small contribution from the cheap seats in helping your mind cut through the crappy wood to see the only really important tree which is in your sphere of influence.