do I tell him?

I've always been into this guy since I was younger, it's never been romantic as we got older as we both were in different relationships (me with his best friend) but we've always had a flirty / love hate relationship. however a few months back we had a one night stand (mostly because I wanted to piss his friend off and bcos I've wanted to all these years) and now I'm pregnant... do I tell him? we haven't spoke since, and I really don't want his group of friends findin out.