That pawn should be snapped off in less than a nanosecond.
And how does it matter if Black knows where white is going to castle.
1) Your up a pawn so OBJECTIVELY you should win the game after such a bad blunder (yes, losing a pawn is a major blunder..don't ever think "its just a pawn")...
What you are thinking is a misconception that should be thrown out immeadiately. Yes, sometimes you don't want to castle early or into an attack in certain positions. But in this case, it doesn't matter even the slightest.
When you play Bxc4, you gain a pawn AND develop a piece. And it doesn't matter if Black knows where White will castle.
1.e4 c5
2.Nf3 c4
3.Bxc4
I was wondering if white is really better off taking the pawn on c4 because then they are likely to castle kingside and wouldn't that make it easier for black to know right away which side of the board the white king is on?