HaBO: He Carries Around a Defibrillator

This HaBO comes from Sarah, who hopes to track down this book:

I hope you can help this smart bitch out.

I read a book in the last 20 years where the main character was trying to leave her husband. He had become so paranoid about dying that he carried a briefcase with a defibrillator in it. I could be misremembering what he carried in the briefcase, maybe he carried a fire extinguisher and he died of a heart attack? Either way, the main character was fed up with him and left and then he maybe died anyway.

I know this sounds like a drama, but I remember it as a tragic-comedy. Definitely more women’s fiction than romance. And I want to say it was a British author, but I’m not sure. I’m hoping the Bitchery can come up with the answer with just these few details.

Can we track this down?