My condolences to you and your family. Like many others, I don't have any special words of wisdom. It is hard to impart any kind of wisdom when someone has suffered a loss. We can have sympathy and even empathy, but wise words seem to be lost.
Having lost parents, a brother and a grandchild, I can appreciate your feelings but have nothing of value to add. Your Life Celebration at the retirement community sounds like a wonderful idea. It is not only good for you, but the friends that your mother had made over the years.
Keep only good memories of your mother, and if there was ever anything that was not so good.....put it out of your memory.