Yes, lots of people use meth and aren't murdering children. I also disagree with the whole "all drugs are equally evil" argument that often gets presented on these threads. Yet look at the mom's Facebook page I linked to above. At one point not far in the past she appeared to be a normal single mom who loved her children. She had a job. She had no criminal record.
WTF happened to her?
“WTF happened to her?”
Yes, that’s really the question. It seems the other woman is well established as bad news, so I guess this might get filed under “fell in with a bad crowd”.