I think Lord Balcain felt all alone and didn't know any other world/society that would have provided him another chance in life had he wanted to live. From the articles on the wall of his place, it appeared that he had a title and little else that he needed to live in his society. ("Scot estate with ghost sold" and he mentioned his relatives were doing "indelicate" things in the country), so it appeared he didn't have any family presently in his life to put him in positions like they did in society then.) When he was cornered in the library, I think he realized how low he had gone and was genuinely embarrassed by what he was doing and what he had become. I think, when leaving, he started to apologize to the men, but then when he said "To hell with you all" is when he decided to commit suicide. It isn't that he wanted to die, but he couldn't see any options for himself or was willing to work to make another life outside his current environment. By printing the lies, it forced himself into following through because his life (as he had known it) was over. Anyway, that is how I saw it.