Depression can be a lonely place, even when you are surrounded with a loving family. I am in the same boat. It is hard for our loved ones to understand depression if they have not experienced it, that is why we feel so alone.
you said that you still can't believe you have it. First you need to claim it. Don't be ashamed and don't let depression define who you are. Have you sought help?
If you need guidance there are people here who can help, including me.