Anger is a very strong emotion. I'm sure Robbin is right right to think that Mary's anger has it's origin in what she has learned to expect of men at Hill Street and in the fashionable world generally, in other words that most men are selfish, consider only their own wishes, and ignore women's needs and feelings. Mary had thought Edmund was different but he's just the same - he wants things all his own way. She could be thinking:

"I've told him over and over what sort of life I'm looking for, but he hasn't been listening to me. He doesn't care about what I want. It is obvious that he doesn't really love me."

Robbin quoted:
She would learn to match him in his indifference. She would henceforth admit his attentions without any idea beyond immediate amusement. If he could so command his affections, hers should do her no harm. (23)

I wouldn't use the word "revenge" for this because I don't get a sense that Mary wants to punish Edmund. I think that here Mary could be seen as protecting her own emotional well-being. She had started to really fall for him, and she's hurt and disappointed that he doesn't love her. She doesn't want to let herself be hurt even more.
There is an incident in next week's chapters which has a bearing on what Mary is saying here in ch.23. So I'd like to revisit this discussion in a week or so.

When I'm pondering on the relationship between Edmund and Mary it is tempting to follow a line of thought which loosely goes:-
It is good to be serious about religion/ethics and morality; Edmund is serious about his religion but Mary can take it or leave it; therefore Edmund is right and Mary is wrong.

It is a valid line of reasoning but I don't find it helps me to understand how things look from Mary's point of view. A modern day analogy for Mary and Edmund's situation might be as follows:

Edmund is a committed environmentalist who wants to settle up-country on some land owned by his father. He plans to farm it organically, and by example persuade others to a green way of living. He needs a girl with muddy boots and a passion for composting.

Mary is a Prada and Manolos girl accustomed to upscale city living among the wealthy, the fashionable and the influential. Her idea of life in the country features luxury living, swimming pools and ready access to a very exclusive health and beauty spa. She thinks 'Why not be a lawyer or something- they make lots of money - or go into politics. We can buy organic food, and you can drive a hybrid car if you must'.

Sigh! It really begins to look like a hopeless case, doesn't it? Sometimes I think Edmund and Mary are conducting a "dialogue of the deaf".