Anyone else hide their depression?

In the last few months, I've really felt my depression worsen. It's been affecting my daily life in several ways. I'm always tired, but I have trouble sleeping. I'm not interested in sex, I don't care about my classes at school and I'm having trouble getting motivated to do homework, study, and apply for graduate schools. My wife has always been pretty supportive of me, but I've been trying to find other excuses for why I'm tired or why I'm unmotivated etc. I don't feel like I can just tell her I'm depressed, she'll ask why and I don't really have an answer. I feel guilty because she's supporting me while I finish college and I'm not feeling motivated to finish. I often feel like she would be better off without me. She does so much for me already, I feel like she would crack if she realized how messed up I am. And I can't point to any reasons why I am depressed. I've got a pretty good life. She knows I suffer from depression, ADHD, and OCD but I don't think she understands how much they affect me.