Hi Fabien,
Right! Give them a good hiding!

There's a really funny (and tragic) story in MCTB, where Daniel recounts how at a retreat, during a group interview, everyone was going on and on about their personal problems and back pains. Daniel got fed up and interjected, "The BREATH? Has anybody tried paying attention to the BREATH?", and they all looked at him, and went back to complaining about their girl/boyfriends.
Chances are, you're going to encounter the same pattern whith your group.
Me, I wouldn't alienate them just yet. Read the "dark night" chapters in MCTB first, and then decide whether now really is a good time to rashly sever your ties. There's a recognizable pattern in that, too. Also, people tend to move at different speeds: maybe you'll be able to encourage practitioners there by example more than by preaching. Just my 2 cents.
OTOH, if you feel out of place at the group, obviously, leave them to do their thing.
Cheers,
Florian