Thank you so much for all your replies, simpsonsChristmasSpecial, you've been through so much. It is hard with it constantly being about them and their needs. Of course we care, but that doesn't stop us needing support too.
Snowleopard I'm glad you found me you've helped so much since all this happened. I really appreciate the continued support.
Totalchaos thank you for understanding why I asked him to leave - and yes it was stupid masculine pride that screwed it all up I know it's difficult for those who have experience of depression to understand how much it affects everyone around you. I had reached the point where as much as I love dh, for the sake of the dcs and the future dc he could not be my priority to the exclusion of everything else.
Lovebeingamummykissingsanta I haven't found support yet, but I will. And I have been in touch with a very close friend who has been brilliant - I just wish she was closer.
choosyfloosy I can completely relate to "the alien in the house" thing. It's so apt. I'm hoping once meds kick in properly he can get a bit of perspective and work things through rationally.
Right. Here's the update:-
He's still here. We started talking Sunday night. His bag was packed for him to leave on Sunday and I was feeling strong and ready (although at the same time desperately wanting him to prove himself and stay). He broke down and we started really talking about, well, everything. He said he would go, but didn't want to. We talked about how he had been treating me and at first he couldn't understand quite why I was so upset. He said he thought about me all the time, but he couldn't give me one example of how this translated into his behaviour.
I talked him through how he speaks to me and treats me, giving lots of recent examples (sadly, there are lots more). We discussed the situations from his point of view as well as mine. So, for a really mundane example, when he was late for something that was important to me (I was very upset) despite promising to be one time, and I was hurt, rather than apologising he shouted that he wasn't late at all and left me even more upset. He then finally apologised 3 hours later after I had "convinced" him that my hurt was real.
From my point of view he had ignored my wishes, didn't care that I was upset and wasn't sorry for hurting me. From his point of view he hadn't listened to the promise he had made (IYSWIM), he wasn't too late, and was angry with himself for forgetting the promise so denied everything and projected his anger at me. He said it was important not to say sorry unless you really are, so he waited until he was sorry to say it. For him the issue was resolved, for me it was not.
It was sad to hear that he gets angry with me whenever I am sad or upset (because he is angry with himself for causing it), but at least now he can deal with that.
Hearing it from his point of view was helpful and we discussed what could have been done instead.
DH suggested that if I'm upset he should go away for half an hour until he isn't angry with me anymore and can be sorry. I asked him to consider that scenario from my point of view and he could see that being left alone was not the perfect solution. It may seem like a really small thing, but dh has been completely unable to see things from my point of view at all. We talked about his feelings and about mine - and he didn't run away. We discussed how him being angry at himself was so much of the problem. He was treating his self-hatred as a sort of penance for all his "terrible actions" (meaning the smallest of mistakes that would be nothing if they were not blown up by him) but rather than punishing himself it was spilling over into hurting me (the person he was punishing himself for hurting ).
Today he has been to the doctor and is now on 40mg. He has finally realised that this is not going to all magically disappear and that he will have to put in an enormous effort (which I will support every step of the way).
I have reached the end of allowing this behaviour and am no longer afraid of asking him to move out if the need arises - but I really hope this is the turning point.
He has been attentive and kind to me for 2 days now. I know that may not seem like much, but he couldn't even do it for half an hour before.
I am optimistic, but realistic. We're going to keep talking. I haven't told him anything new, but he seems to have really heard it.
Sorry about the long and boring recount - I just had to write it out (you're lucky it's not a transcript of our conversation ).
Thank you to everyone who replied. I know there will be more hard bits in the future, but I think we might have a chance afterall.