I would move a bed into his room and sleep with him in his crib until he gets used to it and then Gradual Withdrawal so that he can get used to sleeping there eventually without you. I agree that you should do this, not only for your sake, but for his as he will be disturbed when the baby comes along. It might take a few weeks, but be consistent. There is a thread about teaching independant sleep in the FAQ section on tis board.
Keep us posted, we will be here for help and support.
Good luck with the new baby.