Help!!!!

So I messed up big time and the guy I was with didn’t pull out in time. I have unusually long cycles (35-40 days) and it was about 2 days after my period, should I be worried or get plan B? I know sperm can only live around 7 days or so and I shouldn’t be ovulating until about a month from now. I’m really nervous, and didn’t mean to mess up this bad.