It could be that you have a lot of anger towards your Mom and it's built up over the years. I think you were justified and perhaps don't send her there very often or when she's sick. Your Mom crying is a bit of a manipulation to make you feel bad. She was irresponsible and that is your daughter were talking about. Setting some boundaries with her sounds like a must. Like she needs to clean her house, feed the child, give her the medicine and have her home on time. If she fails to do this then you may want to reconsider having her babysit as your child could get hurt and the environment sounds unhealthy for anyone to be in. Just my thoughts. I also know you can not change your parents. But you can set boundaries to ensure the safety of your child.