You're absolutely right in thinking he's acting overprotective. He doesn't want to share you or lose you. He is probably still insecure and trying to show you he's worth keeping, he he.
Classes and NILIF should help him tremendously, don't be too harsh with him but when he acts protective like this, tell him NO and demand that he sits so he knows you are in control. It's a slow process but I'm sure he'll come around, just need lots of patience. Good luck, keep us posted.