Just thinking back over my marriage due to some issues and awaiting counselling. My now exH used to really pressure me to tell him how many men I'd slept with. I refused to tell him. He'd call me a tart, used goods, and make out I was a whore whilst insisting I was frigid as for for some reason I wasn't too keen on sex with him 
Is it normal for partners to demand this information? He asked me many times over the years we were together. I never told him. For the record it was less than 18 people. Not many considering the 8 years in total I spent at uni.