Should i tell him that thing?

I have a bf and we love each other. We're both good looking and popular...and this guy who is also good looking and he is also the team captain of the football team is my lab. partner..and we work on the project in his house...and he snag a kiss from me and wants me to be his gf....yes...we've kiss for like 2 minutes...but i rejected him..and he said that he can wait...so should i tell what happened to my bf? And i don't feel comfortable working with that guy...