Facebook and relationships HELP!

My boyfriend is planning on opening up a business and he opened up a Facebook. Which I must admit scared me because we have been in a relationship for 6 years and he's never had a Facebook. Now he won't add me on Facebook and he blocked his friends list so I can't see who he adds and doesn't add on facebook. My mom magically found him on Facebook, tried to add him and he blocked her too. I don't have a Facebook but I told him if he's going to have one then might as well I have one too and he said I'm still not going to add you. He said its a business thing and he doesn't need to say we are in a relationship .Basically "bad for business" mind you we've been together for six years. Last time I checked he had his sisters on Facebook, a few teachers from high school and one girl I've never heard of or seen of. When I questioned me he told me he was selling something to her off Facebook. And then he blocked his friends list. When I bring it up he calls me pathetic, insecure and of having low self-esteem.