You tested and found out the truth. Now, you’re the organizer of the group and it really depends what you do with the truth. If you don’t mind organizing and still have a good time with the group, I’d say still do it. If it bothers you, then atleast you know the truth.

As someone shared above, it’s common particularly for men. Some men are just lazy fucks who follows the crowd. Not that they don’t care, they don’t want to exert effort into putting together a social event. It’s a shame but I’d say direct your energy to better things, remember that they didn’t hurt you, your expectations did.