I read it again and still am blundering about the edges of this repartee trying to make it out. :)

So do you think she was sincerely telling him Edmund to accept Mr. Crawford's help, or was her whole statement in jest? If it wasn't wouldn't that mean she was saying take my brother's help despite the fact that he's not really helpful at all? I guess with her playfulness, she could say something like that after all.

Not meaning to be a dope, but she did think after Sir Thomas' harangue and the other, startled from the agreeable fancies she had been previously indulging on the strength of her brother’s description, no longer able, in the picture she had been forming of a future Thornton, to shut out the church, sink the clergyman, and see only the respectable, elegant, modernised, and occasional residence of a man of independent fortune.