Losing someone close to you, big changes?

I'm 17. I live alone with my dad in Chicago. I lost my mom in an auto crash on the interstate almost two months ago. She isn't dead, but she is not involved in my life anymore. She lost her license, her car, everything. She resides in another state under the obligations of court, & jail time. My dad and I are happy with how or lives are going without her. To put it simply, she was an addict who made life at home horrific. She chose her drugs over us all the time. She refused to seek help. Ironically, her accident was a result of these addictions. Because I have lived with this throughout my entire life, I understand that addictions are serious and should be handled as such. With her being being out of the picture, and my dad committing to work with long shifts in order to support us, I have to take care of most everything around the house. I have no problem with this. The issue is that she has told my dad that she wants to come back. Sh claims she's changed after the accident & after 1 week of rehab, yet her sister (she lives with her now) tells us that she's acting the same way as she always has. It breaks my heart to hear about my mom, but I would rather have a peaceful life without her, instead a a chaotic life with her. Is that bad?