Hi Lily,
That's a lot of stuff to grieve all at one time - your precancer healthy self and now your husband. Add to it the fear and anxiety that all these tests bring and it's easy to see (from the outside anyway) why you can't concentrate right now. Most people would have difficulty concentrating with just ONE of the three. Be aware of the five stages of grief and how they may impact your daily life (and the stages can come concurrently and not in order). Most local hospices offer grief counseling and you may find that useful. Private counseling with an MFCC or someone at your church (if you attend one - many churches have "people helper" programs with people that will walk along side you through this) may be helpful. Your burden is certainly something too heavy for you to bear alone at this time.

There are some books that may help you understand whats happening, if you are able to read them, like Elisabeth Kubler Ross, "On Death and Dying" or "Death: The Final Stage of Growth".

I will pray for comfort for you and your family...