I can feel your sadness and heartbreak in your words.

I'm trying to word this so it doesn't sound like I'm making it all about you, because I'm not, it's just the most common issues I've seen as a carer.

When you drop him off do you hang around for a bit saying goodbye? Often if the drop off process is drawn out it makes it worse. A quick kiss, say "goodbye, I love you, I'll come back and pick you up after your nap/ lunch/ whatever" and walk away is usually much less traumatic for them.

Having said that, maybe you could spend a couple of days there with him to help him feel a bit more comfortable with the surroundings and the teachers?

He could also be picking up that you're anxious about it. Which would not help either.

How do YOU feel about the centre and the staff?
Do you get a good vibe?
Are they happy and smiling when they greet you?
Do they say hello to your LO and try to make him feel welcome even if he's upset?

Maybe have a chat to the director of the centre or group leader of your DS's room and see if they have any other ideas?

Failing that maybe it is time to look for a new place/ type of care. Family Day care may be a better option for your lttle man.

Good luck.