hi wally,
i'm sorry you've decided to stop hosting your support group, but if you think that is what's best for you - then so be it. it's not your responsibility if no one else takes over, you never made a commitment to it 'for ever'.
i will say (as someone who has depression) that when i'm in a bad spell, i'm very very very bad at responding to emails/phone calls/facebook messages/whatever. i guess that explanation wouldn't extend to all 150 members, but it might account for a few. please don't take it to heart.
you mentioned that you "are not sure what to do". does this mean you might reconsider your decision?
xo deli