Well that's a little worrying, what's her problem?

Maybe she is trying to say that she hates OP and trying to motion for Her to do so. Be careful

Tell said mother in law not to get too close to the edge, as it would be a shame if she accidentally fell.

#1 that cake look so good!

Tell her it's also a good place to push someone off the cliff.

Don't push me, 'cause I'm close to the edge. I'm trying not to lose my head.

Forget about her it's your wedding so enjoy it!!!! Congrats!!

Don't give that woman any ideas.

that good eh? i might book a vacation there xD

She could just have a fucked up sense of humour.

Yeah, I could definitely see my parents and my partner's mom making jokes like that. Some people just have a dark sense of humour.

Make it your challenge to manipulate her to like you before the wedding. I've done it many times, it's fun.

How many marriages have you been in? One divorce not good enough for you?

Oh no I meant generally, I've never been married thankfully!

Monster-in-law.

Look her dead in the eyes and say "or homicide if you ruin my special day."

BINGO!!

counter with "or assisted suicide", see if she gets that hint as well.

Did she have dyed black hair and excessive amounts of eye makeup on?

Why does that matter?

Failed emo joke...

Generalizing people of any look into them committing suicide just isn't funny. Suicide isn't funny at all actually.

It could be that she IS suicidal, I'd be concerned if a family member said something like that to me.

Morbid much?

Just in case