That's a big step, good for you! I have the same problem, almost every relationship I've had with a man, I've kept most of my thoughts and feelings to myself. Interestingly, I also grew up in an alcoholic and chaotic home. Maybe there's a correlation there?

I know how hard it is to break down that wall. And I've also had the experience of the wall just crumbling one day and then suddenly being much closer to a significant other where I felt like I was finally able to breathe and relax and open up.

Don't feel guilty that he is calling you so often to check up on you, it just means he really loves you. Maybe you can comfort him and tell him you really appreciate him checking up on you but you're okay and he doesn't have to do that anymore.