jman, wish I knew what to say to assist. I've had some very deep depressions at times and the worst of it to me at least is the feelings of powerlessness but I certainly didn't have things as bad with my parents as you have with yours.
Is the group therapy actually helping? Sometimes it can, but other times, one or two people dominate the group and can get too overbearing. As long as the group is run properly and everybody is given a fair chance, I think it could help.
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Break out you Western girls,
Someday soon you're gonna rule the world.
Break out you Western girls,
Hold your heads up high.
"Western Girls" - Dragon