Severe separation anxiety 1 year old

So my son is one, back in April I got meningitis and was in the hospital for a week due to seizures and he stayed with my aunt. Ever since then he is extremely attached to me. Tonight he cried so much at the nursery in church he made himself throw up and we had to leave. I can’t have anyone babysit because he will cry the whole time. I can’t eat out and go to use the restroom because he cries until I come back. I don’t know what to do. I’ve tried staying with him in the nursery a few times to help him, I’ve tried sneaking out as he is playing. This Sunday I’m going to attempt to tell him bye and that I will be back and see how it goes. Does anyone have a baby that is like this? And what kind of exercises or learning can I do to help him calm down? It breaks my heart but sometimes I need to do things and I need to be able to leave him for an hour with a reliable sitter.