[kafkaesq]

When complaining, he says, "if you don't like it, just quit."

He's not only firmly placed himself into asshole territory, with that statement -- he's given you as clear a hint as he can possibly give that he doesn't believe the company has any future, either -- and is essentially trudging on in "zombie mode" for a few more weeks (or at most months). Until it is either acquired or dissolved.

That said -- and being short on time as I write this: if (as I'm suspecting is most likely the case) financial constraints prevent you from simply walking out the door (even before finding another job), then you can at least look into the contract as to whether you are required to be be on the premises "as directed by the company", or are required to work more than the usual 40 hours a week, or similar language.

If not -- the you have every right to tell this guy that it's simply not in your contract to work that many hours, or to be in the office that late.

But tread carefully please, and definitely consult a lawyer before deciding on any course of action.