Emergency last night!

Last night me and my boyfriend for two years had sex, it was normal, he usually cums in me with the condom on then pulls out and everything is fine. Till last night, he pulled out and it broke inside of me & it had only somein the condom when we checked!!! I freaken out and went to go buy a plan b, I've been drinking water like crazy and i made sure i peed right after we had the accident. Any tips and help please!!!