painful anal

so last night my SO and i were making love and my favorite position is from behind. while we were going at it he slowly started to inch his thumb in my ass and it was uncomfortable but not bad i felt like i had a stronger orgasm actually...then the bs came omfg he literally spit in his hand and grabbed his dick and slowly stuck the head in my ass...im constantly panicking but i try to relax, hes not small so its very very uncomfortable but yet he takes it slow...once hes fully inside he goes extremely crazy and hard omfg i felt like i was being torn apart, went on for what seems like hours but after it was over i realized that i had orgasmed...which leadd me to think did i really like it or is it an easier way to try because im interested.