I WENT THROUGH THE EXACT SAME THING WITH MY SON AT ABOUT THE EXACT SAME TIME..UNTIL THEN HE WAS A FANTASTIC SLEEPER BUT IT THE SEPARATION ANXIETY AT BEDTIME STARTED OUT OF THE BLUE..HE WAS FINE WHEN I DROPPED HIM OFF AT DAYCARE, JUST BED TIME..
SO WE DID WHAT YOU WERE DOING UNTIL WE COULD DO IT NO MORE..
THEN WE BEGAN SITTING ON A CHAIR IN HIS ROOM AND I WOULD READ A BOOK OF MY OWN, NOT LOOK AT HIM, NOT TALK TO HIM, BUT JUST BE THERE..I EXPLAINED WHAT HE SHOULD EXPECT AND WHAT I WOULD BE DOING AND IF HE DISPUTED IT, THEN HE UNDERSTOOD THE ALTERNATIVE WAS FOR ME NOT TO BE IN THE ROOM..SO HE BEGAN TO FALL ASLEEP WITH ME THERE BUT LIKE I SAID, NO LOOKING AT ONE ANOTHER, I ACTUALLY FACED THE WALL AND ABSOLUTELY NO TALKING..
GRADUALLY, I MOVED THE CHAIR TOWARD THE DOOR, THEN OUTSIDE OF THE DOOR (SAID I HAD TO LISTEN FOR IMPORTANT PHONECALLS, MEANWHILE I WAS NOT EVEN ON THE CHAIR ONCE IT WAS OUTSIDE OF THE ROOM...
MAYBE GIVE THAT A SHOT...