the further you detach, the less you begin to care about the lies.
Yes, exactly right. Vik, here's the thing, you have GOT to detach. She wants you to take D for 4 days, there are only two factors you should be thinking about- 1. does this cause you any kind of hardship (IE, you'd have to take unpaid days from work or paid days you had planned to use for something else) and 2. would you like that extra time with D. That is ALL you should consider. WHO CARES what your XW is doing with that time, that should NOT be on your radar. I think you're looking at it like you are enabling her "bad" behavior but you've got to get used to this because now that you are separated she's going to be spending more time with OM or OM2 or 3 etc. and you need to be at peace with that. She is probably lying about it because she doesn't want to hurt your feelings, but whatever the reason it doesn't matter. I wouldn't call her out on it or say anything passive/aggressive like "enjoy your meeting". Like the others said, only a yes or no response is required.