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.
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.