From where i sit, you are doing very well!
I know that progress may seem slow, but all this talking with your "not-a-talker" husband is impressive, even when he shares things you don't like (like his fear of having a one-night-stand at a party).
By talking about this stuff when it feels ok to bring it up and without heavy pressure, you are demonstrating the exact skills that would help him feel safe if you actually HAD an open relationship. He is watching you try to be honest and kind with him. He is seeing evidence of how you would work to protect your own relationship with him.
that's major progress.
Leelee, all alone.