Yes, I am highly indignant. The Thorpes may've called themselves her friends but they really cross the line !

They show no respect for Catherine's wishes at all nor any idea of honour.
They knew Catherine had a prior appointment with Miss Tilney yet
the three of them place her under great pressure to go with them.

Isabella comments 'no great struggle' to make Catherine feel guilty.
Isabella had ignored Catherine for a few days, so her attitude quite angers me.

When Catherine breaks away from them, it's hard not to feel proud of her.
She is thinking for herself.
I've heard we often learn best through negative experiences and I think this is the case for Catherine.

However, it doesn't excuse the behaviour of the Thorpes bullying Catherine.
Grabbing of hands to restrain her may not amount to manhandling, they had no right to do it. They do bully Catherine and distress her.
And I see a shade of gothic in the form of the dastardly JT who Catherine fears will pursue her.