Ruby,
My thoughts and prayers are with you and your family. Its such a devastating loss, but I'm confident that you will live through it, and gain strength to grow even stronger during the years ahead.
My experience with people close to me dying is that the grieving comes in waves and continues for longer than you anticipate.... and you just have to go with the flow when the grief comes. I think having somewhere physical you can go to express that grief really helps - whether its the cemetary, or somewhere that was special to you and Matt.
But at the same time, life does gain some normality, and you don't need to feel guilty about that either.
My friend recently lost his wife, and he says that he feels like there are two train lines in his life. He'll be going along OK, and suddenly will "switch lines" and feel the full weight of the grief. and then often suddenly again, he'll be back into the routine of life. You have to experience both fully and not feel bad about either time.
I hope that you have a strong community and family around you who can support you in this time. Please make sure you let people help you - not only will it relieve you of some of your responsibilities during this time.... its also their way of expressing their grief and feeling like they can do something that will make a difference.
Pen