at ages 4 and 5 is when most children experiment with finding out what pleases them and also games of I'll show you mine if you show me your, house doctor and so on so it could have been a noraml play experience. and is quite common. also most children that are abused are through people they trust- relatives, babysitters, family friends and acquaitences. Though alot are abused through strangers a majority are through people known to the child that is why children are being taught in schools as young as preschool and kindergarten about good touch bad touch and their bathing suit areas are their own. so what you went through is quite common. and you are not alone.