Birth Control

Tabitha💗
My boyfriend of 2 years and I found out we were pregnant on Friday the 13th last month. I had been on birth control since I was 17 & still managed to get pregnant. Him and his family seem to think that I got pregnant on purpose. What can I say to him/them to help them believe me? Statistics? They seem to think that it is impossible to get pregnant while taking birth control.. HELP!