I write message on whatsapp to stranger

I wrote few messages with girl on fotka.com (something like tinder and badoo). Girl is from Nigeria. She gave me her whatsapp’s number (with localization based in Nigeria). I downloaded whatsapp and wrote 1 message. Now I think it was silly and very,very irresponsible! And know my question is: what can be done with my number? Does someone can use it for something? Please answer me.