I went through (almost) the same in 2017.
My mother died just one week before christmas, on december 17. Due to brain tumor. She was 64 years old. This was very quick. It all started at the end of the summer, at the beginning of autumn. At first, she was in hospital for a few months. Then in hospice in another city. I regularly visited her in the hospital, and I brought her food and fruits to her, like bananas, but I could not visit her in hospice. I also have regrets. I wish that I should have been more kind to her, and that I have been spent a lot more time with her. She made everything she could for us (for me and for my brother). She worked throughout her life. Even when she got early pension. She made everything to make our lives good. She deserved much more from this life. This is a hard topic. I have a lot of regrets. I made many (intentional and not intentional) mistakes in my life, but I am trying to be a good person.