18 mon old just weaned from bottles-now not sleeping, please help!

jwc2008

Two weeks ago I stopped using bottles cold turkey (per the peds advice, since I should have done this at 12 months). Prior to this, DS was a great sleeper, he got a bottle at bedtime but was always awake when I put him down, and would roll around in his crib until he fell asleep on his own until the morning.  Since bottle weaning, I have been giving a sippy cup with milk at bedtime which he takes, but the second i stand up to put him in the crib he screams bloody murder. We have tried letting him CIO up to an 1.5 hours, rocking, patting, combo of the above, nothing seems to be getting him back to the way he was. I know i have to be consistent but i dont really know how long i can possibly let him cry for until i feel bad and go in to pick him up ( and most likely wind up in our bed). Sigh. Just feeling frustrated and exhausted and in need of ideas and encouragement.  Thanks in advance!