Why would the group die if you stop going? Are you the only other member besides the pushy lady? That's alot of pressure on you alone....and nobody should have to bear the entire burden of keeping this group together.

Maybe after she's had some time to calm down and think about it she'll change her viewpoint and not think that you're being ungrateful....just realistic. If not, I'd just tell her that having MS is enough....you don't need more stress and pressure. If she won't take constructive criticism and other ideas for the meetings then she's going to find herself alone. Not too many people will keep going back if all their ideas to help are poo-pooed.