Im promiscuous..and i want to change! help me?

recently i cheated on my wonderful boyfriend with a guy..,my excuse? my boyfriend is out of the country. Now this guy is making funny advances on me again. and i want him to stop. but im scared that if i confront him. he'll tell other people about what has been happening and ruin my name..what do i do? how do i stop giving in to so easily? how can i be faithful?