It is a very difficult situation to be in. Watched my mother slowing die over a dozen years, to hear of her passing on a college field trip. One does what one can, that is the best that can be hoped for. You had someone who could help with the weight of her, which would have been beyond me.
Hired a hospice worker for my mother-in-law over the 20 months of her demise. Called daily, saw her most days as well.
There is no way to get around the relief of not having to do something that is hard, whatever that may be.
Remembering the difference between the body that was your mother and the spirit that IS you mother may allow you some ease with your grief and your loss. We are physical beings, in part, and all physical forms decay and disappear. In illustration, the Appalachian Mountains, at their heights were taller than the Himalayans are now.
Peace comes as it does, embrace it, remember the love, in all of its forms, and be happy for the inheritance that gave you. Go slowly, returning to life is never easy.