HELP! Unprotected Sex!

So my bf and I had some unprotected sex (which we NEVER do) and he pulled out and said he had to finish himself off which only took a second- he does this even with a condom. He swears up and down he pulled out before precum and even said that if he hadn't touched himself after he pulled out that he wouldn't have cum. But I'm a worry wart and have really bad anxiety and getting pregnant cannot happen right now. I took some vitamin c right after because I read that it can terminate a pregnancy and I figured the earlier the better. I just got off my period today so it isn't even my fertile window but I'm panicking. What should I do?