Our situation came to a head when my MIL caused an accident that could have killed our newborn. All we wanted to do was talk about it and the general concerns we were having. DH was going to talk to her alone so she wouldn't feel ganged up on. She reached exactly the way you described. Difference was that that time the incident was so serious that we couldn't let it slide without a conversation. Three years later she's never agreed to talk about it, and we've kept our word and never let her be alone with her grandkids.