dude seriously dont get DRUNk just a couple of drink to boost your confidence. Then just talk to the girls the sameway you would if you were still with the girlfriend, as if you dont really want to get her in bed just enjoy nice conversation... pretend to your self that you are still in a relatioship. then when i girl is having fun and enjoying her time you'll know what to do.

If that doesn't work dont forget to scream SURPRUISE before you put it in