Yorick, you can't at the same time say that it hadn't made things awkward, and that you make sure you don't see her alone, and no more than once or twice a year ! Besides, it bothers you all right if it has made you post here. So maybe you feel uncomfortable, both with her and with her husband, your friend, for nothing, if she is no more in that state, if it had been only a fling due to a brief unbalanced emotional state. And last, isn't it you that stated with much energy that truth was better than ignorance ?
I say, if you want to feel comfortable with her AND with him again, make things clear with her.
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The world is my oyster !
And now I have the knives to open it ...