He lied to me

Boyfriend told me he hasn't had sex but I found out he did have sex and a foursome. Not sure if both or just the foursome but yeah. What do I do? I can't tell him how I found out. Should I just ask him how far he's gone and see if he lies? And if he lies I'll be like I got told otherwise. ? It doesn't bother me that he isn't a Virgin it bothers me that he lied and still hasn't told me