DS1s nursery had a 'mummywindow', which we could peep into to see the children playing happily once we'd gone. Ut was a great nursery as they really looked after the mums there too. It was very reassuring to see them having fun, particularly if they were a bit sad when we left them.
You will feel sad to leave him, but you can also get great joy out of seeing your little man making friends and having fun with other children.
Best of luck. We will be thinking of you/praying for you.