Sometimes, for you own good, you have to set the rules. A painful experience for me: my mother moved in with us when we returned from overseas deployment in the army, to be with her grandchildren. A couple of years back, we told her to move out. Turns out it was the healthiest thing for our relationship. My wife and her no longer butt heads as badly, I feel a little less weird and my children now love their turn staying the night with her. While your situation is different than mine, I am just saying that oftentimes setting the boundaries is painful in the process but healthier in the long run. I sure didn't feel good about myself at some points during the process but sometimes we have to do these things for our own sanity.
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God grant me
The Serenity to accept the things I cannot change,
The Courage to change the things I can,
And the Wisdom to know the difference.