What does it matter? A) She's your ex, isn't she? or B) I suppose if you're worried about respect, and all that jazz, you could leave it a week or two, just to let things simmer down. I'm assuming 'recent' means 'days' and you found this 'someone else' before you broke up? If so, then yeah, I'd leave it a couple of weeks, otherwise, don't worry about it and just move on. Life is too short to stand around worrying.
I suppose it depends who you are.... If you're Wayne Rooney then your new bird has probably already told your ex - who just happens to be her granddaughter </p> If you're Henry VIII avoid the issue completely and lop her head off. </p> If you're Bill Clinton then she may already suspect something's going on with your zip down, **** out and semen splashed everywhere. </p> And if your girlfriend is Mystic Meg, then she already knows - probably even before you did.</p>