Tell her you're going to dinner with your sister. Leave it at that. If you say, "we are separated", you might as well tell her she ripped your family apart.
If she dares to push for a reason, tell her you gave it a lot of thought. It's best for the boys if they are not getting mixed signals, and going to your sister's for dinner is best to help them avoid confusion.
D, zip your lips after that. Firm, friendly, and strong. No R talk. You don't want a discussion about it.
