I'm sorry things are so bad. Another example of the unmanageable mess we can get ourselves into.
It's not your job to fix anything of the domestic arrangements. As you've explained it, you were hit on, you went to bed. If I'm reading this right, the only thing you could have done better was not put yourself in that situation in the first place.
My advice is to focus on yourself - don't drink - don't put yourself in that situation again.
I have a feeling your bf and his brother will sort out the rest of it, one way or the other.
D