You could try self-defence/provocation
It's the knife that makes it tricky.
I suspect a jury would let you off.
( WormuIus, Tue 17 Aug 2010, 12:04, 1 reply, 16 years ago)

I certainly wouldn't actively look for a knife
but it was in the kitchen and I could have been legitimately holding one at the time.
( Peej, Tue 17 Aug 2010, 12:05, Reply)

Did you genuinely believe that your wife was going to be seriously hurt?
Was there anything else you could have done?
( WormuIus, Tue 17 Aug 2010, 12:07, Reply)

He's mental she definitely fears for her life now
I'm pretty sure if she was alone she would be dead. Some old family feud about money. There obviously was something else I could have done because I did it but I'm just saying that despite me being a reasonable person I am pretty sure that if I happened to be holding a knife at the time I would have stabbed him without a seconds thought.
( Peej, Tue 17 Aug 2010, 12:09, Reply)

If he hadn't died
you'd have been fine.

If he died, possibly not.
( WormuIus, Tue 17 Aug 2010, 12:11, Reply)