Oh SQ you are describing a very common pattern of behaviour for someone with depression. I think it's harder for men because they tend to "not believe" in depression and certainly therapy is usually a "NoNo" too and their quest is to get better without any diagnosis or help. Sadly there is still a huge stigma around mental illness and this all comes into play when we are depressed.
I think you have to be assertive about the meds and insist that he takes them, as they are in the main very affective and he is not giving himself the chance to get well again. OK depression is said to be a self limiting illness and 4 out of 5 people make a full recovery in 4 - 6 months.
I really can empathise with your DH as the things you describe could well be descriptions of me when I have bad days - I am irritable/angry and scared and crying by turn. This is the confusion that depression brings with it - it's like our brain has been taken over by a stranger and we are "not the person that we were before the depression" and this is the reason he is questioning himself about his relationship with you. It really isn't that he doesn't love you and I think you have to try hard to believe that, and tell him that it is the depression "talking" and not him, and this might be something of a relief to him.
I totally get how he feels he can't cope with the children - when I am having bad days (my depression is intermittent) I don't feel I can cope with the cats! Many young mothers on here are having to cope with young children when they are depressed and god only knows how they do it, because I'm sure I couldn't but I suppose if there is no option they have to get on with it.
It does takes all our resources to cope with every waking hour when we are depressed. It is difficult for anyone who has bot suffered the torment of this illness at first hand to even begin to understand it, but believe me it is one horrendous illness.
SO I think you should be firm with your DH and tell him that he must take the meds as they are likely to get him better (and back to the loving DH that he once was) more quickly. We become very self absorbed in our own emotions and are unable to empathise very well with others, but that's the nature of the beast I'm afraid.
Re the weekend away - yes it could be a good idea, but then again we often feel that we can "get away" from our depression by moving somewhere else and of course this doesn't happen. But it would be a time for you two to talk. Try asking him gently to describe how he is feeling, and be firm about the medication. Tell him he owes that to you and the children.
Oh and I urge you to read up about depression and go on the MIND site that has a wealth of information.