Hi @Annette11, welcome to the forum.
I do have a bit of experience in this area, but from the 'person with the aggressive cancer' point of view.
It's hard for everyone involved. Everyone deals with these things in their own way and their own time. People want to help, but don't know how or what to say. From my own experience and that which i've experienced from people around me since was diagnosed, my advice would be don't feel like you have to, or can, fix everything.
Sometimes there just is nothing anyone can do to help while people process what they are going through. It's not what you say that matters, it's just being there for her and for whatever she needs. Just being there lets her know she's not alone. Don't push her to do anything she's not ready for. Maybe suggest some small things, like going for a walk or ask her out for a coffee. It may be just to sit there with her. Just be there for her and keep checking in and let her know you're there if she ever does need anything. You may feel like you're not doing anything, but you are the one there for her and that often means more than anything.
Often with these things, it seems to be hardest and more frustrating for the people trying to support someone, than the person being supported. She may not be ready to accept anything right now, or maybe even for quite a while, but by being there throughout her grieving process will help her and hopefully with time it will help her start to heal.
Maybe someone very different is just what she needs right now to add a little 'light' to her 'darkness'.
