Frettingagain I think unfortunately you may have to turn elsewhere for some support, there might not be a right time for you to talk to your DH even though you need him. I'm afraid for a while this may be a lonely road to tread.
My DH has snapped at me sometimes as I have got lower and lower in my misery. He can not cope with his own grief whilst watching mine as well. It is truly awful watching someone elses grief and wanting to take it away but also having your own to contend with.
My DH needed to get back to work to get some normality back in his life. Albeit a different one from the one he and I wanted. It helped him, it helped me to be a snivelling wreck whilst he was out the house but put a brave face on when he was around. Over time we learnt to overlap our coping mechanisms, he can now support me when I am having a moment and I can support his "time out" This has taken time to get here.
Unfortunately for men it seems getting back to "normal" ie work and routine is part of their healing process whereas for us women me it seems getting back to "normal" feels like we have moved on and forgotten about our loved one and that is soooooo not the case.
There is no way my DH would see a counsellor it is not his thing however much I or he would feel it would help. I on the other hand have seen a counsellor after my father died suddeny a few years ago. It helped me to talk to someone outside the family and get my head round some things but I know it is not for all.
I think your GP has been helpful, can you ask for a referral for counselling?
I think normal rules do not apply here in this situation and all of those "leave now" have to walk a mile in our and our DHs shoes before they get a full comprehension of the situation. I don't think he will do it again, I think he has probably shocked himself and has lashed out as he is hurting.
Do not get me wrong I do not condone physical violence but I do think there are extenuating circumstances here. If this was just a slap then take note, be aware and if it happens again or escalates in any way, get yourslef armed with some cash and a change of clothes so if it happens again you can get to a safe place with some resources to assess the situation in safety. I do feel though that this will not happen again.
If you had a happy relationship before your recent troubles I would say you can work this out together, possibly in different ways but you can get there. DH and I have been on the brink of divorce a few times since our loss and we have been at the depths of such horrible despair and misery and both of us have felt loneliness even whilst together. We have come through this stronger and are now even thinking of having another child.
I appreciate having DCs to carry on for has really helped me and I think this may not be something you have and this makes it all seem so much worse. But give yourself time, you will get there.
I am thinking of you and your DH and send much love CM