End your relationship with this man and move on with your life. Life's too short to deal with an oxycontin-addicted guy who goes "crazy" who has a baby with a "party girl" who smokes oxy "all the time" even through pregnancy. That is not the team of horses to which you want to hitch your wagon.
Kenny Rogers told us "you gotta know when to hold 'em, you gotta know when to fold 'em" -- I think you're in the latter category at this point.
Good luck.