Thanks for your question. Many people wonder about semen and underwear.
Sperm can live outside of the body for a short amount of time, except in very specific conditions. Good news is that sperm won’t survive a normal cycle of a washing machine. So, you do not have to worry about it contaminating other clothes.
Semen stains usually come out of underwear with a normal cycle of a washing machine using regular clothing detergent. If the stain is still there, try washing your underwear again or try using a stain remover for clothes.