This is a highly personal moment, so keep it that way. Don't involve anyone else.
"Don't break up when other people are around - friends, or even strangers," advises Ariane. "This is between you and him only, so don't do anything in public that might cause him even more upset or shame."
Wait until you have some time alone together, somewhere quiet where you won't be interrupted - his home is probably the best setting.
Obviously, he should be the first to know, so don't tell your friends about your decision first. These things have a way of coming out, and he deserves to hear it from you.
Keeping things private also means holding off on the flirting until you're completely through. "Don't start another relationship or sleep with someone else before you've ended things," says Ariane.
We certainly hope you wouldn't - that's just plain rude!