I'm sorry, (((((Amber)))))). Not because this is a Greek tragedy, but because no matter how an individual reacts to loss -- it is always individual -- there's an inner child present there somewhere. Hugs and gentle company to her. (I'm glad Buck's with you now. And that your mother's misery is over.)
That child may feel relieved, scared, sad, guilty, confused, liberated, angry, lost, numb or any of these and so many more emotions. It's such a swirl for a while. Individual.
I like Lighter's thought that sometimes more healing and closure happen after a death that could not happen before. Something that occurs to me is that no matter our age when it comes, when our second parent dies -- even or maybe especially a toxic one -- on some biological or metaphysical level, being orphaned is a new identity. Sometimes even when we've looked forward to that freedom, it is still a disorienting feeling. That wears off.
I knew when my Nmom died my main feeling was relief. I had already done most of my grieving for her (what she was and couldn't be) over the course of years. I was also exhausted; so some sorrow, but no tears. Now and then I very briefly miss her, just in a momentary flash when, say, folding something the way she taught me to.
You just do you, wherever your feelings and reflections take you. I know you'll listen to what floats up and you'll be safe with it.
hugs and comfort,
Hops