"And you don't have to pretend you'll miss me."
"Of course, I'll miss you. You're my mother."
"Well, that's very dutiful of you considering that I've never been very loving towards you. And I'm sorry for that but you've always been a great disappointment to me, Claudius."
As for being half-witted: well, what can I say except that I have survived to middle age with half my wits, while thousands have died with all of theirs intact! Evidently, quality of wits is more important than quantity!