How do you get past negative responses from someone with dementia that you were caring for that have stuck with you?

It sounds like your mother and you had a good relationship -- not something I would expect if people didn't love each other. I have a feeling that gladimhere is right. She didn't realize what she was saying. Another thing is that the disease could have affected her brain so she wasn't feeling love. Alzheimer's changes people so much that they can become like different people. If you know your mother loved you when she was well, it is what matters. If you loved her is even more important. I suspect that people who can love are lovable themselves.

SuzieM
I'm so sorry that you are dealing with this particularly harsh memory at the same time you are grieving the loss of your mother. I don't think I have the words to tell you how to forget what you heard or for it to not make you feel alone and lonely. I remember hearing Harry Belafonte sing, "Sometimes I feel like a motherless child" and I imagine that is what you felt like when your mom said that. I also wonder what was the state of your mothers mind when she spoke those words that were so hard for you to hear. Perhaps she realized that she didn't know who you were. Perhaps she remembered something about love but couldn't put it together with you as her brain was no longer functioning in a way that would allow her to remember. Perhaps it was a loss that she was sorry about or something she thought she should tell you. Perhaps she saw how much you were caring for her and she felt it only fair to let you know. Perhaps she heard something like that on tv and was only repeated something she had heard. Perhaps it was something someone had said to her. I know it won't make those words fade for me to write these words but your relationship was much more than those few unfortunate words and was for a time much longer than those 13 years or that last six months. It has not been long enough for the last months to shrink to their appropriate size in importance. Those few words seem to weigh more than all the rest of your relationship, but that's for now. They still loom large in your mind. They will recede. My own mother has been gone for two years this month and it is just now receding and I have yet to be able to remember better times, times before illness and death. We go into a sort of trance in our care giving. It takes a while to come out of it.
I do know that for you to dwell on those words is not healthy for you.
You may have heard this story. An old Cherokee is teaching his grandson about life.
“A fight is going on inside me,” he said to the boy.
“It is a terrible fight and it is between two wolves. One is evil – he is anger, envy, sorrow, regret, greed, arrogance, self-pity, guilt, resentment, inferiority, lies, false pride, superiority, and ego.”
He continued, “The other is good – he is joy, peace, love, hope, serenity, humility, kindness, benevolence, empathy, generosity, truth, compassion, and faith.
The same fight is going on inside you – and inside every other person, too.”
The grandson thought about it for a minute and then asked his grandfather, “Which wolf will win?”
The old Cherokee simply replied, “The one you feed.”
So turn away from those words and that experience and think on more pleasing times with your mother. Its hard to stop doing something. Easier to start doing something that pushes the other thing away. "I am love" could be a mantra you could repeat when the memory comes back. Something simple that you can repeat over and over. Therapy might help you as well. Hugs

Suzie, those with dementia often say things they do not mean or understand. I am sorry mom said this to you. Understand, though that mom's brain was broken and I am sure she did not understand what she was saying. A caregiver needs a very thick skin and often times very hurtful things are said by the loved one. I am sure she did not understand.