The only way to know for sure is to take a home pregnancy test. While the fluid that men secrete prior to orgasm can contain millions of sperm, the likelihood of any surviving in the hot water and then being able to swim into your vagina is pretty low.
But I've heard of stranger things. Better to err on the side of caution, just to be sure. And in the future, don't expose yourself to sperm without using risk reduction. Dr. J