"She was honest and said that she feels unhappy and sometimes she thinks she would be better off if she was alone because she doesn't know how to interact with me anymore."

She sounds frustrated. My mom said that same thing once when I was twelve. She left me with my dad a few months after and I watched her out the back window as my dad drove off. I truly believed I made her so sad that she didn't want me. Turns out, she was going to get help and get better so that she could be a better mom to me. I didn't learn this until I was eighteen.
I don't think you have to worry about your mom leaving you but I think that your mom is in a similar place as mine was. Wanting to figure some way out to be able to understand, again, maybe? I don't know, I'm not her but she does sound similar to that certain experience with my own mother.