Oh Possum! I lost my mum some years back, but what you said resonates with me.

It was several months before "it" hit me. I left that "I can't believe she's gone" stage and moved into being angry with her for leaving. Then, at the same time, I'd turn around and remember how she was just all worn out, and couldn't go on. I would and still do feel gratitude that she was no longer suffering.

Allowing myself to feel these feelings, name them and know that they are mine and mine alone is worthwhile work.

Do talk with your T about what you said here. Mine helped me so much. I wish the same for you.