It IS a cruel thing to do. As for "How has he become a General?" Well, look at the modern military! Surely there are enough examples even now of idiots in the ranks to make a statement like "miliatry intelligence" an oxymoron. They can't all be like our WilliamL, you know. ;-)

As for his anger, I suspect the answer is "all of the above." I think he does have the capacity to be angry with himself but perhaps not to realize it. Because he wanted Catherine to be an heiress and thus a rich prize for his son, he's angry that this hasn't materialized and thus he take it out on a blameless target: Catherine herself. He can't vent on John the Bloviator because the boofhead isn't there. Catherine's presence is a reminder of his mistake, so he throws her out.