it is horrible situation to go thru....
"one of his plans involved taking us all out and that terrifies me"...thst is awfully scary - have you been able to talk to
a) his psychiatrist about this and
b) talk about it with your own counsellor? your GP should be able to refer you for six free NHS counselling sessions. mine was extremely helpful (it also made me aware of may other huge issues in the relationship but that's btw). yes you qualify as a "carer" but make sure you take up support available.
how old are the children?
are you able to up and leave with them if he should get scary? does he display agression or violence or is it just talking about it?
there are various books on dealing with depression in a partner ...
www.amazon.co.uk/Living-Black-Dog-Matthew-Johnstone/dp/1845297431 etc.
anne sheffield depression fallout is more weighty but excellent lots of research chapters on effect on children and how to mitigate (eg make sure they spend time away from the depressed person with "happy" people, lots of breaks etc)
www.amazon.co.uk/How-Survive-When-Theyre-Depressed/dp/0609804154/ref=sr_1_2?s=books&ie=UTF8&qid=1281 007606&sr=1-2 as first review says:
The problem with all the advice that you are given as the partner/child/parent/friend of a depressed person is always "be caring understanding and supportive". What no-one ever said to me before I read this book is that it's really hard to do those things when you're not getting them back in return. It was so wonderful to hear out loud that, yes, depressed people are selfish and self-centred and difficult to live with. As well as offering a truely helpful insight into the depressive's situation, this book validates all your feelings of frustration and resentment and tells you how to cope with them and look after yourself.
you need to look after yourself in all this - and the children. put them first.
remember - it is your fault adn it isnt what you did - and that as a n adult he has to take repsonsibility for addressing it.
and keep the mental health crisis team number in your mobile and remember you can always dial 999 should you ever feel scared. (thinking about when you might use that option helps you actually do it when thetime comes)
if he does need to be admitted then let it happen. dont protect him.