Actually, it sounds already ruined. You may have provided a finishing blow, but the battle for the soul of the group was already lost. You have at least one player who doesn't want to play and is acting out, at least one player who wants to be casual, a DM who wants a serious game, and yourself who I didn't get a read on.
If you want a serious game like the DM, talk to him about starting a different group and spend the times this group of friends gets together doing something else. Otherwise, just spend the times this group of friends gets together doing something else.