I'm so glad you have your sister there for right now. Yes, it will be complicated for a little while. But eventually things will settle down. Did your mom have a will? There will be legal things to take care of at some point--I'm just wondering whether that will be your responsibility or whether there is someone else who will take care of winding up her affairs?
Just keep putting one foot in front of the other. It will all get accomplished. Just keep reaching out to us as you need to.
Hugs! It sounds like you did a great job of comforting your mom at the end.