I'm confused about why you are stuck in their home. Can you not call a taxi and go back to your own home? In any case, drinking is the last thing you should be thinking about. It won't help anything and will only give the family more reasons to consider you unfit to be a part of their family.
Personally, from what you've posted, I think you can do better than that group of hoity toity snobs. He wanted his dad to "test" you? Really? Pffftt...