The thing is, she was never mom to begin with. So she can't be mom "again". She just broke the illusion that she let you have for a while.

And you do have a mom. Just a crap one. You didn't get what you needed and wanted from her, which sucks. But now you're an adult and you have someone in your life who cares and is trying to support you.

The more you try to live in the present instead of the past, the more healthy of a relationship with your LC you can have. You say that nothing has a changed, and that's a lie: you have the beginning of an honest relationship with your LC now which you did not have before.