Mudgey you just explained why I feel so draw to their forum like a nutshell!
About your family, I know know its hard to explain to people, especially your family. My family still doesn't really understand mine. When my gran found out she snapped at me and angrily asked why I'm depressed and I couldn't explain to her that it's not that my life is particularly bad its that I don't feel good enough and it was taking over and keeping me from enjoying life. She still doesn't understand it, but I've decided to talk to the members of my family that don't make me feel threatened about my depression.
My suggestion would be to talk to the ones you feel most comfortable with first. Or maybe even sit them down and have a reverse intervention. If you're seeing a therapist maybe you could ask them to help you in explaining it in a way they will understand and as back up.
Just remember that you are accepted here and we'll always be willing to talk if you need to.