Tunapie I am so sorry to hear this.
My dear father died of a heart attach when I was pregnant with dd. I worried the shock of it would make me lose my baby, it did not, and she is now 12. His loss did slightly taint the arrival of my beloved and long awaited child.
However, I do really believe that we can try and manage our grief and sadness, sometimes and for me his loss was very much part of normal life in that he died in his 70s from natural causes. Sometimes a death can really be very dramatic due to the the age the person is or the reason they die and in those circumstances I really think we need more help, through counselling, to come to terms with this.
Can I please suggest that you seriously consider some bereavement counselling. It may well be helpful to you in coming to terms with the emotional side of the loss of your mum.
However, there is another emotional side and that is when you say "...my husband is in a sulk the whole time then holds it against me years later." This is really worrying.
I would also suggest if you cannot find an amicable solution that supports you and recognizes your needs here that you suggest a relate or similar appointment to work through this together with your dh.
In terms of the practicalities...
If he will be out of the house from 7.00 to 7.00 then I think you will need help and company too, this is something your dh needs to understand. You may not be able to get out and about to toddler groups etc, friends may not be free to visit so you may find it quite hard and isolating.
I'd talk about it with him and see what he suggests for help.
I'd suggest:
-Your sister staying with you but on the understanding she skedaddles up to her room when he gets home so he can bond with baby
-Your sister in a B and B at night but coming over to see you daily
-A mother's help to work for you temporarily (being paid for) to help you
-A cleaner to work for you temporarily (being paid for) to help you
My mother did not come and stay when I had dd (by C-section) and I would have found her quite difficult as she was recently bereaved (having lost her husband, my dad).
My dh was very supportive and certainly was not out of the house 7-7. I think your dh needs to understand that you may well need some support and if he cannot give it, then he needs to help you find it.