What to do about my cold sores and the resulting depression?

I am a man who gets cold sores on my mouth and they are coming more often now. At first, I didn’t think it was a big deal but now I am getting more embarrassed and depressed about them. I feel gross, repulsive and ugly and it feels like the whole world is staring at my sores.

I know this sounds petty but I cannot help how I feel. I work for myself and I am considered a smart and nice person but I cannot shake the depression that has come over me about this. I have one now and it hurts badly and I have a fever. I have no appetite and I am exhausted. I think my mental state is making my physical disease worse. I got so tired today that I had to lie down and I never sleep during the day.

My girlfriend has noticed that I am not myself but I don’t know how to tell her this without her thinking I am crazy about stressing about these stupid blisters so much.