Okay, so we know that his 'cry for help' was nothing more than a cynical attempt to avoid taking responsibiity for his actions, but by draping a cord round his neck and holding his breath periodically until you appeared, he's shot himself in the foot.
When you talk about his mental health with the GP, say that he didn't 'cry for help'; he tried to kill himself and if you hadn't happened to have gone into the room at that precise moment, your appointment tonight would be for the purpose of collecting his death certificate.
Say that you fear for his mental health as it seems to be in a precarious state and it is your belief that he needs urgent pyschiatric treatment as an inpatient.
Explain to the stupid twat doctor that if you hadn't intervened, it may have been that one or all of your dc would have discovered the dying or dead body of their df and that they are at risk of severe emotional harm due to his mentally unstable behaviour.
You are best to keep on-message and don't allow yourself to be diverted should the quack come up with more half-baked theories about the role of the little woman to be a mental health nurse to her afflicted spouse and take full responsibility if she's unable to police him 24 hours a day, or some such crap.
If the quack runs true to form and spouts more garbage just keep reiterating the above and - in particular - ask him to note in your h's records that you have expressed serious concern for the state of his mental health to the extent that you fear he will take his own life if he doesn't get treatment - INSIST that this gets written in your h's notes.
As for yourself, forget about Relate - at the present time this is not about your relationship with your h as much as your relationship with yourself. Ask the GP to refer you for NHS counselling which is free.
Unfortunately, there's usually a long waiting list and it may be some months before you get an appointment for assessment. In the meantime, continue to ask any questions here as the collective wisdom of this board will provide the answers you seek and will, no doubt, also answer questions that you haven't yet thought of.
When your world is filled with crap, look for the straight unpolluted path that will get you away from the stench.
In your case, the path is one of firm resolve to take no nonsense from your h or from misguided and ill-formed professionals and get him out of the house so that you can have time and space to process the recent traumatic events you've gone through, quiet your mind, and give consideration to how you want your life to be.