Although protest, she knew, was useless.

All this, however, she could have borne.

The thing that she could scarcely forgive was the slight offered to his native town by a departure three days before the set date, thereby turning his "going away" tea into a "gone away"-- an action considered by all (invited) Bainbridge as a personal insult.
Pause here for breath.
To continue.

Your Aunt Caroline does not believe in rest cures anyway.
She thinks poultices are much more effective.

It stands to reason that if a thing is in, it ought to come out.