Is my girlfriend cheating on me?

ok so my girlfriend is a little slut , we started dating when we were 12 and that was in 1979 since then as far as i know the little whore has only slept with me but who knows, our week goes mon-friday i drop her off at work at 6 am, i pick her up at work from 7pm and i have the foreman in the mine watch her very closely hes my father, then on the way home i stop at a strip club and leave her in the car she thinks im going to confession , then we get home i put her in the basement and give her her water, on the weekends she spends her time pleasuring me then going back down to the basement , is there anyway this little butt slut is messing around behind my back? i know she is thats why i wont marry the juicy loosey