Can sperm pass through underwear.

Hello doctor. My bf ejaculated himself and washed throughly using only water , and then he wears thin cotton shorts only and we done hugging , I was wearing my nighty and my underwear. He was rubbing his penis from inside of his cloth at my ass and my anal point for 2-3 min ( I also wearing my clothes (nighty and underwear) . So my question is , when he's rubbing he felt that his penis is still little wet and the shorts had little wet spots , that could be sperm or water which is used to clean , we don't know. He done for sometime. Till now we can say that he didn't taken his penis to my vagina or near it. It came only my anal point from back side of it. So my question is will the wetness whether the water or sperm or the mixture will travel from his little wet patch shorts to my cotton nighty and into my underwear and into my vagina to get me pregnant. We are so scared. It's on my 10th day usually I get periods from 30-35 days . We are so scared Pls answer will sperm cross cloths