Scooby - yes, I think it's time to set some type of boundary. Make it extra clear that cannot and will not happen in your house. My H and I have a vacation home 3 hours away, and I'm beginning to suspect the same thing. I haven't been there in several months (it was closed for winter) but am planning a visit next week, and won't be telling him much ahead of time. If she has been there, I WILL know.
Time to have a very serious talk with him Scooby. Thinking good thoughts for you -- must be extremely stressful daily existence at your house at the moment...
Me 53, XH 57 M 20 (+1.5) years, no kids BD June '13 H moved out July '13 Confirmed long-suspected PA Feb '14 H filed for D Nov. '14 D March '15