Are you seeing a psychiatrist or therapist? Try to accomplish 1-2 things a day, even just 1 to start off with because it will make you feel better to accomplish something. You can't take care of your family if you aren't taking care of yourself. You are feeling as a failure to your family but it's related to you failing yourself. Take care of you so you can help take care of them.
Are you taking an antidepressant?