Anyway, I thought this was totally irresponsible and so I called her and left her a voice message (she never answers my calls and rarely answers her kids calls) saying something like "I can't believe what you are doing, leaving the kids alone after not seeing them for over a month. This is totally unacceptable and irresponsible. The kids are a red-line and I will not allow that. Please be responsible and take care of your kids."
You will not allow it? Unless you have something legally to back you up, be careful of the words you use.
You have no authority to tell her what she can or can't do. The two of you are physically separated. If there is something legal in writing about her not leaving the kids alone, then you can take her to court or whatever.......which gets expensive if you take her every time she shows bad parenting, but that's your choice.
What I see is you trying to shame her. It's not your job. You can't shame her into being a good mother. She doesn't have to live her life according to your values.
With that said, I am not blaming you for being upset. It is a bad situation when a parent is wayward. I'm just trying to caution you about how you address some of these issues.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!