There is no way to revert to an earlier version in Steam; you need to have made a backup of the game before the update (either through Steam or by copying the install folder to another location), or have paused the update download, to delay it.
Tenebrium is needed to deal with the attack on the homestead, but will not help with the demons there directly.
I sent you a PM after your first post: in the top text menu (under the banner) click on My Stuff and select Messages.
