Steam Families has just released out of beta and is now available for everyone with a Steam login. In a lengthy post on Steam, Valve outlines the new uses for the Steam Families system. Essentially, it's a way to share games with up to five additional Steam users.
You can start a family very easily, and you'll all gain access to one large library. But, before you go trying to all play one game at once, it's worth noting there are a few caveats. In the post, Valve uses the example of one user playing Portal 2, while another plays Half-Life 2. Both games are in the same library, but neither one can be played by two people at the same time.
There's also the issue of developers choosing which games are shareable. If you and your friends are going to pretend to be a nuclear family to get cheaper games, developers might restrict access from their game being shareable.
You can join another family or create a new one if you grow sick of your current one or get kicked out (yes, that can happen). However, you'll need to wait a year from leaving the last family before joining a new one. So, it's probably worth thinking about whether you're just going through a phase or whether you really do hate your family before you leave.