Please show some self-respect and get back in control, even if you 'really like him'.
Ignore him, totally. If he says hello, you can give him a very small recognition that you see him and nothing more. You just need to 'walk on by'. Do not flirt, do not expect anything, do not involve yourself with this immature young man. Even if your aching inside, you need to show some pride and self control. Believe me, you will heal. But the way to get things started is by withdrawing.
Its time to take control.