My wife and I are struggling with a situation involving her sister. Let's call her Suzy.
Suzy is an alcoholic/drug addict and is in a relationship with another alcoholic and physically abusive man, and has what we would classify as anger issues. She is very easily irritated, and becomes irrationally angry at whomever she perceives as the source of her anger. She is seeing a therapist to address the underlying issue but has made it clear she has no desire to stop drinking
Recently Suzy has began expressing interest in taking our 3 year old child places, such as libraries, shows, movies, and to her own house for a sleep over party. We are fine with Suzy visiting, where things are monitored, but we are not open to Suzy taking our son alone with her.
My wife loves her sister, but is struggling to find a gentle way to tell Suzy that she may not take our son due to the above reasons. She does not wish to destroy her relationship with her sister, but has found herself avoiding Suzy to avoid this subject.
I've suggested to my wife that she "blame" me -- and tell Suzy that I am the one putting my foot down on this, but she doesn't want Suzy to hate me either.
We wish to tell Suzy we are fine with visits at our home, but we are not okay with her removing our son from our home alone -- without damaging the sisters relationship.
How can we get this message across to Suzy without causing even more problems?
Update
My wife had her chat with Suzy about our concerns using dbeer's approach (honest and up-front, but no blame), and part from Francine's answer (history of bad decisions); and to our complete and utter bewilderment, there was zero confrontation. They have agreed they will go out together with our son until such time we deem she is fit to supervise him alone. Thank you!!!