Hi Helena
I do feel for you being so down at the moment. I'm still comparatively new to all this so have a lot to learn - but it strikes me that one of the saddest things for those of us who had less than perfect relationships with our parents prior to their illness, is that the illness takes away any chance of 'making good'.... and there is that bit of child in us that wants acceptance right up to the end. I can see how your mother's rejection of your card hurt you.
In my situation, I always had the impression that I couldn't do anything 'right' in my mother's eyes. I'm certainly not doing anything 'right' in her eyes at present but it is easier for Mum to vent her frustration, confusion and unhappiness on me than to deal with it any other way. I don't think she can now. She is beyond what we would call logic.
When Mum went into the EMI unit, I felt it was because I had failed (again), but my DH helped me to shift my thinking. At first I thought he was being unfeeling when he told me to be more emotionally detached. He told me to do what I can for Mum as if she was 'any' very old person in great need.
So what I've tried is to mentally step out of the box that was full of the pain of old and unresolved issues and into something more objective. I may well have to step back in there and sort it out later - (Some nights at 3am the contents sneak over the edge!) - but for now, it helps ME to know that I'm doing the best I can and the effect has been that I'm not as tense when visiting and can offer more physical comfort when needed. That can only be beneficial to Mum at her current stage.
I don't know whether anything I've said here will work for you. Such a learning curve for me at the moment. I could have a different view a few months down the line. However, Dear Helena, there are lots of people here sending e-hugs to you and you will be in my thoughts and prayers.