Can he tell when we have sex that ive been cheating?? ?

ok so me and my boyfriend, husband really..we've been living together for about 3 1/2 yrs, have been apart for 4 months since hes been in jail. before this our relationship a lil rocky with a lot of fighting between us. Recently since hes been gone ive had sex, a few times, and hes already thinking this is happening and he wrote me saying that he'll find out when he gets home and we have sex. is he right ? Can he tell? One guy was bigger, two about his size, and the other not so big. Over a period of 3 months.. :/ and now hes coming home in 2 more wks and I havent had sex in a wk.