Don't know where to turn
20 months ago my partners younger brother passed away and he is not dealing with it at all. He has become distant I would even say estranged from me and has become very short tempered with our children (and most other things). At this point in time I am ready to walk away from our life together as it feels like I am here only to be his maid and child minder. He WILL NOT seek any kind of help and I'm at a loss as to what to do.
Stop trying to control him. Every time you force that idea of help onto him he's gonna reach into his hole (along with the temper). Depression is depression !
Most depressive sufferers are very, very, very, very, very, very hard on themselves. So even if you're just saying something practical like "You know Mary's been seeing a great counsellor just around the corner from where Des lives" it's gonna be received as a major criticism not just off his behaviour, rudeness, you over mothering and controlling him but also it doesn't accept the fact that his younger brother passed away and there was nothing he could do about it. He must be still grieving heaps to be so isolate and make you think of walking out. Your husband didn't ask for the depression.
I don't think it matters if your are his maid and child minder. The guy can't function at the moment and you seem fantastic at holding the fort together. If you were suffering in the same way and not making much progress I'm sure he would feel that he was the butler and child minder. But in your current situation you probably can't think of "what if it was me that had chronic depression from a personal trauma ?". Would I cope with a demanding partner seeking a quick fix ?
It's a good thing to get this way and maintain the depression because it prevents a further escalation and possible suicide. He's in a holding pattern. When he feels ready for help he'll ask or at least say "I can't go on like this - take me to the psychiatric hospital for an assesement".
I'm long term bipolar and have had multiple admissions and the one's that always recover first are the ones that don't get quizzed or given a sort of "why are you better yet - you've been in here 2 months already ?". It's better to arrange simple things together - meals, walks, kids taking bikes to the park, DVD nights, fast food, pizza, washing the car together, basically anything domestically OK. His depression might/will pass with a bit of unconditional love and the right treatment. You really can't ask for anything more. If his brothers death was very sudden then I'd say 20 months is fine. When our children grow up and move out they reckon it takes 2 years to adapt.
Sorry to not give you more "read the riot act" advice but in the meantime you could seek counselling yourself and find out how to deal with your growing anxiety. If "HE WILL NOT seek any kind of help" then maybe you should. Your kids don't need two parents not coping. Small changes happen when partners give up the justification and start living with a bit more gentle loving. It's not his fault he can't cope - depression has been proven to give people a brain fog so expecting him to think as clearly as you is really not helping. Get the kids to make him breakfast in bed or draw pictures with him slumped over a chair. Put the person back into the family and leave the depression alone. It can't hang around forever but your family can.