At the moment, he's looking at you as the mother figure (authority). He's possibly projecting on to you how he feels about his own mother. Oh yes, he's grown up, but he's hit an icy spot on the slope that is making him question his life and he's looking back and not in the present or future.
Read the subjects that I suggested as well as what HaWho suggested. Also, read up on gas lighting. They are good at that little behavior too, at times. Keep in mind the stages are just that...stages and each MLCer will do things differently and yet spit out very similar words along the way. Keep in mind, the stages are either written by someone who went through it or witnessed the MLC of their own spouses. Sally Conway has a good book as well and I believe I identified it on the reading material thread.
Once the process starts, it's difficult to "stop" it. I would certainly try not to enable him. He has to learn to grow up and you can't do that for him. Read the Dance of Pursuit and Distance thread. That will help you better understand some of what you may have been doing and now need to slowly cease.
