I have a selfish pleasure in saying he has been called mad

'I have a selfish pleasure in saying he has been called mad, or I should not have had the benefit of his society and advice for these last ten years and upwards - in fact, ever since your sister, Betsey Trotwood, disappointed me.' (My bold.)
Source: http://www.literaturepage.com/read/davidcopperfield-239.html

What does the clause in bold mean?

It means that, for some reason, the fact that an unspecified person (or people) have called the unspecified "him" mad, has given the speaker some degree of pleasure, and they consider that pleasure somewhat selfish.

Can you see how some further context might help here? We might be able to give a more complete answer if you'd told us who the speaker is talking about and why there's a reference to them being "called mad", and what the relationship between the speaker and the "mad" person, and the speaker and listener is.