Seems like your Nana doesnt know how to deal with death.
I would just not worry too much about her, since she seems to be one that likes having attention focused on her. Her actions are tacky, but dont give her the time and energy of your thoughts and feelings....she'll figure it out on her own.
Once again, Im sorry about your loss.
As for your relationship, I would say that right now, youre in a bit of a fuzzy state of mind, so any decisions that you make now, might come out of emotions of the situation that is in front of you. What I mean by this is that your mom WILL get better, she WILL get through this, but you have a life too and that should be respected. Sure....spend time with your mom, but don't throw away a perfectly good relationship is my pt. I really think you should talk with your other half on how you are feeling and really air out everything that is going on in your head. Adam should be understand to your circumstance....when was the last time you guys saw each other? Just curious.