She has lived in the UK for over a decade. A large chunk of her adult life. She doesn’t seem like a cold mean person who no one would want around. Pretty confident she had friends, activities and a life beyond her kids in the UK.
For all her being Canadian after what 15 years abroad between the UK and Asia settling back in Canada wouldn’t be easy. Not returning to her job or to old friends. Life moved on in Canada too. She is not a recent transplant she has been an expat most of her adult life.
It truly is sad news but hopefully the announcement is true and divorcing as friends. Makes for coparenting much easier. We see the York girls how better adjusted they were in ways as their parents divorce was amicable.
As for Beatrice wedding it stands to be seen. Divorced members are not automatically off the list. It seems to depend on the relationship you had with the divorced member. Almost twelve years in the family officially she should have a relationship with the cousins.
William didn’t invite the exes. But Harry had two of his three former aunts at his wedding. Fergie and Victoria were both present (only 2nd countess Spencer was not).
To be fair she probably still considers Canada home, its where she grew up etc, just because she has lived in the UK for many years (and I imagine she enjoys living there) she probably misses it a lot. It must be hard living away for away from your immediate family.
Edward did not invite Fergie to his wedding even though they got on well IIRC, however I guess that was understandable given the time he got married. But Autumn is not really a prominent member of the family so it would really be indifferent if she was there or not. Surely the Royal family would be use to inviting former in laws, they have had enough practice.