Is it against official US policy to negotiate with terrorists, then why are we doing it?

Republicans are threatening to ruin our credit rating and collapse the entire US and world economies by not raising the "debt ceiling", if they don't get more perks for the 2% of richest amongst us. Why is Obama negotiating with them? Why does it seem to me that since Mitch McConnell stated that his only prerogative is "to make sure that Obama is a one-term president", GOP is willing to burn down America just to make sure they can blame Obama for it? Unamerican, traitor, corporate welfare, Koch suckers.