I think you need to ask him to get a
CETV (cash equivalent transfer value) for his pension.
I suggest that you try not to react to what he says and save
responses to be presented in a calm and measured way after seeking advice
on here. He'll then know that you're doing your research and are not going
to be walked all over. He sounds like a bully to me.
Does he
have reasonable grounds to give up work for health reasons? If he's just
threatening it to get out of you getting your fair share I don' think it
would be viewed favourably in court.