You can't be a doormat unless you decide to be one, and having been one in the past (even a few hours ago) doesn't mean you have to be one from now on. Tell her when she returns that this is it. Go to a motel, take your niece if she is still there, or just you go as soon as your niece is no longer at your mother's house. Tell your mom never again. Just be thankful she doesn't sell the car before she gets home.
I know and honestly before I moved away I had gotten very cold to her. I would call her on her lies and flat out tell her no. She is one of the main reasons I moved out of state bc there is just so much drama that goes along with being her daughter. I get followed by police bc I'm related to her. It's ridiculous. We are going to stay with my sister (all my family lives in the area thank god). My SO will be down at the end of the week. I feel so bad that he has to see her like this. She used to be a very strong independent woman. The kind people gravitate towards. Now she is just a train wreck slowly digging her own grave. I refuse to be a part of it anymore.
My biological mother is the same way. Its really sad! I ended up just cutting her off all together because she won't stop and I'm not going to keep putting myself threw the emotional stress I'm about to have my baby and she doesn't even know and honestly I don't want the drama around me, my husband or my baby. Sometimes you have to let people go it doesn't mean you don't love them either it just means you know they won't change so you have to do what's best for yourself
I feel ur pain. I still haven't come to terms with my mom and her stupid choices. I just keep getting colder and colder towards her.