Okay, trying to be even-handed.....

[FeelingFestiveCheerMum]

Okay, so details of family are......DW is long term anti-dep, self harm, alcoholic, suicide etc, Dh is emotionally closed, quite hard-faced, described by loved ones as "cold"

They have one dd, whom they both dote on.

I know Dh doesn't love dw anymore and dw is so far gone she doesn't know what day of the month it is. Neither wishes to hurt dd and both still are care about each other in a detached kind of way.

So what would your advice be?

my advice would be to keep out of it if neither of them are you and there is no danger to the child..

Advice about what?

Assuming you are one half of the couple, get an appointment at your local health centre and take it from there. Your partner should be doing the same. Sort out your individual issues before worrying about your relationship with each other.

If you're a third party, assuming you're close to them in some way rather than an acquaintance enjoying the drama, there still isn't much you can do. But it would be worth being there for their daughter, so she has one vaguely stable adult in her life. However much her parents love her the crap they're currently going through is going to affect her.