My ageing mother and recent death of my father.

So sorry for your loss

1. People deal with grief differently
You are not the same person as your mother so expecting her to deal with your father's passing the same way you did is not realistic.

2. Your duty to take care of her

That is a very broad statement and a questionable one depending whom you ask

It doesn't mean you have to do it yourself, if you choose to do so

Making sure she is taken care of also fulfills this expectation, you do not have it to do it yourself

3. Your mother saying she is fine
What can she do by herself?
Is she independent?
Has she asked for your help and what kind of help?

4. Does she know and feel you resent her?
Your feelings come loud and clear here, so having a person who feels this negatively about her does not help the situation

My father died nearly 2 years ago, my mother didn’t want to be involved in funeral arrangements, to attend the cremation or have any suggestions for flowers, hymns etc.
They were both in the same nursing home, in adjoining rooms and she declined seeing him in the days preceding his death. Her choice but not easy to deal with especially with strict Covid regulations regarding visits and trying to plan everything.
I visited her while the cremation service was underway, she didn’t mention him once nor want to watch the video footage. I found it quite strange after nearly 70 years of marriage but she had it as she wanted.
Mum died 3 months later, in those months she didn’t talk about him at all until the day she died when she told the carers he was standing in the corner of her room.

You need to accept your mother’s choices, and offer help for when she wants it. Little more you can do I guess.

I agree that people deal with bereavement in different ways and it does sound as if you are judging your mother for being different. You prefer to express your emotions and feelings openly. Other people retreat to a safe place like a wounded animal and find other peoples emoting unbearable.

It doesn’t mean they aren’t feeling pain in a very deep way. Perhaps too deeply to be able to give you the support you clearly feel she should have given you.

Why not just ask her what she would find helpful from you. And then accept what she says.

Really you are transferring your needs onto her and wanting her to feel and act as you do.

You are also bereaved and in pain but your mother is not the person who can help you. Would you consider counselling?

Maybe your mum wanted to be alone with him when he died and not be in a joint hold with you and your husband. You say her behaviour at the end upset you, it could be that yours upset her.

If your mother needs help from you she will surely ask. As you have only had occasional short visits you do not know much about how she lives daily and if there are friends and neighbours involved in her life that will offer help if needed.

Maybe your mum wanted to be alone with him when he died and not be in a joint hold with you and your husband. You say her behaviour at the end upset you, it could be that yours upset her

That is an interesting point - did you at any point give her time alone with your father so that she could say goodbye to him with just the two of them there?

Everyone deals with grief differently, perhaps hers is so profound that she feels unable to deal with it and is suppressing it.

Why do you think you need to " cope" with her? From what you have said, she is not making any demands on you is she?
Just let her know you are there for her if she needs it and let her grieve for your father in her own way and stop being cross because she is not doing it your way.

Maybe the only way she could deal with it was to distance herself, and personally from what you have said I think this was it, dad made you next of kin because he knew mum couldn’t deal with it and that’s your answer She couldn’t deal with losing him just as a very hurt or upset child will sit curled in a ball in the corner of the room she sat quietly at the end of his bed not interacting she was numb completely and utterly numb
Maybe you ll never know everyone is so different in grief but I think you are wrong to blame her

When my beloved grandad suddenly died after he left for work my Nan never saw him again she could not go to the funeral I think it was all too final for her and too overwhelming I was then 16 and I said I d sit with her at home quietly which we did
Many years later the same happened with my Aunty (not related to Nan the other side of the family) and again I sat with her talked about my uncle made her cups of tea etc until she said I m ok you go home now and I did

As for future help be led by your mum 82 isn’t that old these days and if she says she’s ok that’s what you need to be guided by continue to invite her but don’t take umbridge when she refuses, because she will Stay close as possible but don’t overwhelm her with trying to look ‘after her’

But most of all don’t blame her or be cross with her for dealing with her beloved husbands death in a different way to you she can’t do it your way

Losing one's parents, even one by one, is a upsetting and unsettling experience, especially when you have clearly had a happy relationship. Having also to help with support your surviving parent can put extra pressure on you and you have my sympathy and condolences.

But I would give you to quotes from your OP:
Mum and dad were inseparable (together since 15 years old), joint at the hip, lived there own life, popping in and out of our family life as and when they wanted,

Dad gave the doctors, hospital, care team etc me as a named contact and named me as next of kin as he had said mum couldn’t deal with it all.

No one knew your mother better than her husband and partner for 67 of her 82 years. He knew and understood how she would respond to his death, when he made you next of kin. He said she would not be able to deal with it all and he was right because she has behaved exactly as he expected.

It is the same with 'popping in for cups of tea'. Some people and families do this without a second thought some people, in the most loving families find this difficult to do. It is difficult to explain, because I am like that and cannot tell you why.

Your mother was clearly totally psychologically dependent on your father and he knew, understood, protected her and loved her. Now of a sudden, that lifelong love and protection has gone from her and she is lost and alone. Nothing can be to her what her husband was.

Respect your father and his knowledge of his wife. Accept that your mother is more different to you than you ever realised and let her grieve in her own way.

I am one of three sisters when one died in a road accident, my way of coping was to deal with anything that needed dealing with and keeping myself too busy to think. My sister retreated to her home and walled herself in with red wine bottles for six months. We may have been sisters, but we have different personalities and we grieved differently.

You clearly loved your father, and he loved you and his wife and did what he did for a reason. Respect it, even if you do not understand why your mother acts as she is.