"I never saw any one so shocked. He could not speak a word for full ten minutes. My mother was taken ill immediately, and the whole house in such confusion!" …I do not know of any other designs that he had formed; but he was in such a hurry to be gone, and his spirits so greatly discomposed, that I had difficulty in finding out even so much as this." (Chapter 47)

I think Susan L is right that Mr. Bennet is a bit shell shocked after he receives Mr. Gardiner’s express just as he was when the initial express came informing them of the elopement. I am not so sure that his shock is not mixed with other emotions however. His initial shock at the midnight express is soon followed by rage:

And as to my father, I never in my life saw him so affected. Poor Kitty has anger for having concealed their attachment… (Chapter 46)

and frustration:

Rendered spiritless by the ill-success of all their endeavours, he had yielded to his brother-in-law's entreaty that he would return to his family… (Chapter 48)

then short-lived remorse:

No, Lizzy, let me once in my life feel how much I have been to blame. I am not afraid of being overpowered by the impression. It will pass away soon enough." (Chapter 48)

Mr. Bennet had very often wished before this period of his life that, instead of spending his whole income, he had laid by an annual sum, for the better provision of his children, and of his wife, if she survived him. He now wished it more than ever. Had he done his duty in that respect, Lydia need not have been indebted to her uncle for whatever of honour or credit could now be purchased for her. The satisfaction of prevailing on one of the most worthless young men in Great Britain to be her husband might then have rested in its proper place. (Chapter 50)

and finally a return to indolence:

He had never before supposed that, could Wickham be prevailed on to marry his daughter, it would be done with so little inconvenience to himself as by the present arrangement…That it would be done with such trifling exertion on his side, too, was another very welcome surprise; for his chief wish at present was to have as little trouble in the business as possible. When the first transports of rage which had produced his activity in seeking her were over, he naturally returned to all his former indolence. (Chapter 50)

All the while still holding on to his anger:

His letter was soon dispatched; for, though dilatory in undertaking business, he was quick in its execution. He begged to know farther particulars of what he was indebted to his brother, but was too angry with Lydia to send any message to her. (Chapter 50)

In Chapter 49 I think Mr. Bennet is shocked by the ease which the entire matter is resolved but also glad, hence the return to indolence. I think his other emotions besides anger are frustration, embarrassment and mortified pride. His love of independence has been imposed upon and I think he finds this difficult to except; it is mentioned at least twice. Where pride never kicked in to exert control over Lydia’s wild behavior his pride now is worrying his conscious:

"Yes, yes, they must marry. There is nothing else to be done. But there are two things that I want very much to know: one is, how much money your uncle has laid down, to bring it about; and the other, how I am ever to pay him." (Chapter 49)

He was seriously concerned that a cause of so little advantage to any one should be forwarded at the sole expence of his brother-in-law, and he was determined, if possible, to find out the extent of his assistance, and to discharge the obligation as soon as he could. (Chapter 50)

The only individuals Mr. Bennet showed any feelings whatsoever for throughout the elopement crisis is Lizzy and Mr. Gardiner. He tells Lizzy that he does not hold a grudge about her advice to refuse Lydia permission to go to Brighton in Chapter 41 and he thanks Mr. Gardiner for “the kindness of his brother, though expressed most concisely” in his answer to the express in Chapter 50. He never comforts his wife or his daughters and could barely give Jane any information in Chapter 47 before leaving Longbourn for London.

"And Lydia used to want to go to London," added Kitty.
"She is happy, then," said her father drily; "and her residence there will probably be of some duration." (Chapter 48)

Mr. Bennet seemed fairly dismissive of Lydia when he dryly told Kitty in Chapter 48 “She is happy, then” and when he replies to Lizzy “Yes, yes, they must marry” in Chapter 49. Although Mr. Bennet’s believes Wickham is “one of the most worthless young men in Great Britain” I do not get the sense he is more worried about Lydian than he is about pride. Is Mr. Bennet truly unemotional about Lydia or does he just think there is no use in crying over spilt milk—she must marry him to regain her reputation, her sisters, and the families as well. Lizzy and Jane have to persuade him that Lydia should be noticed on her marriage by her parents because he is still angry enough to refuse the request in Chapter 50. Up to this point (Chapter 50) I cannot help but think Mr. Bennet’s emotions are pretty much all for himself. Any thoughts? Have I missed something to date which gentles Mr. Bennet’s attitude towards his youngest most undeserving daughter. ;D