I would suggest you go ahead with your plans with teaching. She keeps doing this type of behavior and could continue doing It indefinitely.You cant stop living your own life to clean up after her,over and over, grandchild or not. Worst case scenario, at some point, you take custody agreed upon with her and get lived in help. Or go cold turkey and let them tough it out.
They might do this again and again. You could report them to child services if it bothers you too much.
My son said to me this week regarding my ex acting oblivious about health care issues: stop enabling him. There must be some balance involved,but it really made me think. You know all those rules. What will allow you a life?