That's all part of any illness, short term or long term. It can bring out the very worst in us. And it is not that we are unsympathetic to our loved ones, but sometimes just very, very frustrated over our own situation. And they are very frustrated too, just wanting us to get better.
And it has to come out and when it does, it is those very ones we love the most that get the brunt. Those are the ones whom we know we can be our total selves with and they will still love us. They may not like our behaviour at that given moment, but it is the love that helps them understand and cope and forgive and stay.
I'm sure your Missus knows that what you sometimes say is not a personal attack on her. It all balances out in the end. At least it does for me. I know that sometimes I hurt my fiance's feelings when I am having what I call a "coal day". (I have diamond days and coal days) and when I realize that I have hurt him, I try my best to apologize for my verbal snaps or snide comebacks. Sometimes I wonder why he still wants to marry me and then he will say..."its for better or worse and I love you unconditionally."
I have this really comfy, cozy feather bed in my own doghouse. I highly recommend one!