can sperm swim through clothing?

I don't know who the dad is!! I am almost certain it is my husbands but i am not 100% sure. We have been trying for a baby so this makes this all the more worse for me. my last period was 10.5.2015 (period cycles 28-29 days) We had sex week beg 18.5.20 all week and i had sex with another person on the sat 23.5.15. Any possibilities on who the dad is. I am wondering whether to have an abortion...

Can sperm swim through water?