I'm with sagemother, sometimes you just have to let them cry things out. I know it's heartbreaking for you, been there done that, but he has to learn to go sleep on his own without you in there with him.
By all means, make sure that his physical needs are met. Then go through your routine. Tell him it is time for bed and you expect him to stay in bed and go to sleep. Determine a suitable "punishment" if he gets up and tell him what that punishment will be. If he gets up, make sure you FOLLOW THROUGH! He is being willfully disobedient, and needs to know that disobedience has consequences.
Another option would be to determine what he REALLY wants - a toy, book, trip to the zoo, etc. - and then tell him that he has to go to sleep in his own bed without mommy. Each night that he does that, he gets a star. Do this every night for about a month or so (or however long it takes) and tell him that when the chart is all the way filled up, he gets that item/trip.
We used that tactic with my boys to get them to potty train. And, it worked, they both can potty by themselves now.
