Ive been bitten by my own dog and need to know how to respond?

My dog was resting on the edge of my bed at night when I got up, turned out the lights and as I always do, went to pet him on the head and kiss his nose. Well, I must have startled my 7 year old dog since he immediately growled then lashed out at me. I pulled back in fear and immediately felt my mouth filling with blood. I drove myself to the hospital, needed 18 stitches outside my mouth (on my upper lip) and 4 inside. Ever since I am terrified of my dog. We had a very affectionate relationship where Id ask for “puppy kisses” and he’d immediately come running and lick my nose. How do I begin to address what has happened & keep myself safe as well as regain trust in my dog? I can see him already confused as to why I have been so distant and no longer allow him to sleep in bed with me.