It sounds like there is a lot of fear on your part in this relationship. I remember when I was terrified of my brothers finding out I was going to AlAnon....and discovering in my meetings and reading that it was further evidence of my codependence that I even had that fear! That anxious feeling you're describing is something I learned to leave behind.
It just took time and practice and that fear went away. And it's always OK to keep your cards close to your chest - if you aren't in a frame of mind to have these big discussions or you're afraid things will go off the rails then protect yourself- keep your recovery close and safe if you need to, there is no rush and ultimately as you grow you really won't care what he thinks of what you are reading or doing because you'll become strong in your conviction that this is just about you - it really is not about him.
Are you able to get to any AlAnon meetings?
I read whatever the hell I want in front of my BF and he is either interested or not but I don't live in fear of his reaction, if I felt I needed to hide my interests or pathways to self-growth from him that would be a red flag to me that I was in an unsafe and unhealthy relationship...
stay strong!
peace-
b