To be honest, since you're already divorced, I would MOVE ON. Letting her move back in so easily -- esp. when there are children involved -- was NOT wise ... at all.
If she wants to possibly get back together at some future date, I would rather see you suggest dating each other -- non-exclusively -- for a period of six months or so, and see how it goes. Less confusing for the kids; far less traumatic on your heart.
