I have been through grief, losing my Dad. He was ill for a while, before he died.
He was EVERYTHING to me, just as you described your Gram. Almost to a "T".
My Father, was the only one, who has ever truly accepted me for who I am... all my life. And he was always happy, whenever I walked in a room.
For that, which he instilled in me, I an eternally very grateful.
But what I have also learned is this:
Not everyone, no matter how close we may be to them, whether it is via marriage or siblings or close friends... no one single person... can 'be' all that we need, at times of sadness and strife.
As such, we need to reach out to others... to those who CAN provide that comfort to us. Some people can do that, some can't. Even if it may be a Husband.
Unless your Husband has a history of belittling you or ignoring your needs or being mean.... I would, not consider his reaction, as being cold. Maybe, he is just not able... to deal with death or illness. Not everyone can. MAYBE he is also saddened by your Gram's condition... but he can't express that. Maybe, he is affected deeply as well... but, he has his own way of dealing with it.
But... not everyone, can be an "everything" to someone. Even if that is your own Spouse.
I learned that, even in my own life. And from reflecting on my Dad's life... and him in conjunction with his own marriage and his relationship with me/my siblings. And me in my own marriage.
Not everyone... is an "everything" all the time. My Husband is not, always.
But... it does not mean, they love you less, or not enough, or not good enough... it may just mean, that they are imperfect. And, we must accept that... even if in our own Spouse.
Again, unless your Husband has a HISTORY of being a jerk to you... I would not, condemn him off the cuff.
Perhaps, he just cannot fulfill that in himself nor for you... in this type of grieving....
BUT, ultimately, I believe it does have to be discussed... with your Husband. Not in an accusatory way.... but just so THAT... there will be no resentment... in the future... about how he and you handled this and such deep sad feelings.. about your Gram. It can either divide the both or you... or not. But, I feel, your Husband does need to know, how his "coldness" makes/made you feel.
I also recommend, finding a 'grief support' group. I am not saying because she is dying or passed on... but because, it will help, with these feelings of coping... with such big changes.... and in a sense her illness and change in quality of life... does, trigger a sense of "grieving' for your past experiences, together and what was. You and Gram.... are and always are.. special.
You are very lucky, to have that relationship with your Gram. With someone in your life like that.... I miss, my Dad, just for that reason. It can never be replaced. So, you accept that....
Thank you as well... for helping me to again, remember my Dad. Tonight, as I read your post.
I often wish... I still could experience, his happy smile on, whenever I walked in a room. I miss that.
all the best,
Susan