You’ve been put in a hard spot being given this information but being unable to betray your 2nd daughter’s confidence, I can’t imagine how that must feel.

You’ve received a couple of replies that I think are very wise, but you haven’t replied so not sure if you’re reading them. Not much I can add other than to say as a mother of an adult I would urge you to stand back and see the big picture, not just the devastation this affair will bring, but think perhaps about how things might look and feel 10 years from now. By that I mean how do you want your relationship with her and your grandchild to be?

I don’t have experience of the situation you describe, but I do have experience of harsh words said in the moment- trust me, they stay with you, and that relationship is never quite the same again. You’re very wise to pause and to come here to seek support. I hope things will work out.