Condom broke but he pulled out when he noticed it. i had some spotting over the course of four days and period is due tomorrow. could i be pregnant??

It's possible: It's certainly possible, but the chance remains pretty low (under 10%) just going by usual chances of conception after a single episode of unprotected sex. If your period does not arrive when it usually would, then a pregnancy test is the thing to do. Otherwise there's no way to tell just yet, so try not to worry, and be safe going forward. Remember Plan B is always an effective safeguard.