Yes he had an ex wife. I believe that he said he was happy that it happened. Though it ended poorly he said that if it never happened he probably would still be in Jersey(don't quote me) and never have met Griffin. I think this is what he said but I don't remember where I heard it.
Geoff's ex wife was a really self concerned and demanding person who would always think of herself. The reason why they divorced is because she didn't want Geoff to work at RT. So he divorced her and started fresh.
Realise this is an old threat, however, geoff and griffon have been married since 2005, lets just just assume they took 1/2 years to get married from being engaged. that puts his marraige ending in 2003/4 which is about the time rt started which I (have no real idea about but will make an assumption anyway cause internet) feel like is correct. also I recall geoff getting married at 21? and him being born in 75 puts his initial marriage at 96 so i assume he was married for anything up to 6 years. That being said nobody knows her name because geoff only reffered to her as 'my ex-wife'.
Geoff also said that one time he and Griffon were having sex, he said his ex-wife's name instead of Griffons. He was so ashamed of himself that he swore to never say her name again. That's why he only refers to her as his ex-wife.