I have a game (Awesomenauts) that I can play because it's shared from my friend. This game became free for the weekend as well, but I was kicked off when my friend logged on even though it's free. I cannot start it again and it's definitely a bug, but I was thinking perhaps I can opt out of my friends library somehow, preferably temporarily?
Since you are family sharing, click on the steam icon in your tray, then click settings, then click the Family tab and you can then continue to opt out of this. If this is unavailable to you, you can tell your friend to remove your PC from the authorized PCs list on the same settings page.
As for being kicked out, you are kicked off of any multiplayer/online games if there is more than one person using it at a time when doing Family Sharing