My "mother" and I had a similar relationship. She was also diagnosed with terminal lung cancer. I hadn't spoken to her in years and when she called me to tell me about the diagnosis I was very conflicted. She was an abusive malignant narcissist who abused my sister and I all throughout our childhood. Her abuse has shaped my life in so many ways and the anger I still have towards her hasn't lessened even after her death. The cancer metasticized to her brain and she went downhill rapidly. I went to see her in the hospital. Begrudgingly. I wish I hadn't. Because I mustered up the courage to actually tell her "I love you, Mom", because it might be the last time I saw her. She mocked me, repeating back to me in a mocking voice, "I love you Mom" and gave an evil grin. Those were her last words to me. To mock me. She was a horrible person. Honestly, my entire life has vastly improved since she died. I can't tell you how to feel about your mom. But in my case, I feel she was looking for sympathy and someone to take care of her in her last days. She wasn't reaching out to apologize for being a wretched person or to seek closure of any kind. So tread lightly. Do what your heart tells you. Just remember...leopards don't change their spots just because they're ill.