During a talk which was supposed to focus on raising money for conservation work, John Cleese launched a tirade against his estranged third wife.
The 68-year-old comedian asked the audience at Bristol Zoo: 'Guess how much I'm paying her at the moment?
'I'm paying her £900,000 a year. And we had no children. It really is astonishing.'
Cleese faces claims for half his earnings, half of his nine properties and £900,000 a year from 63-year-old American psychotherapist Alyce Faye Eichelberger.
His mother Muriel, who died in 2002, also came under fire during the extraordinary outburst.
Their strained relationship was well known - and he once credited Miss Eichelberger with helping him come to terms with it.
He told his audience: 'I did have a dreadful mother. Isn't that a terrible thing to say? But it's true. She was classically self-centred. Always thought entirely of herself.
'And she lived to 101 - I thought I'd never get rid of her.'
Cleese blamed his wife's lawyer for turning their separation into an embittered dispute over money, saying his wife is now 'taking me for everything she can get'.
He added: 'When I told my friends, they just put their head in their hands.
'I've suggested it would be much easier and more fair if we went to mediation. But I guess Alyce is just feeling very insecure and wants to get everything she can.'