So... am i being too sensitive? Do i have the right to expect that it's possible to be friends with my Domina as well as her sub? And that there will be the common courtesy/respect that friends have together?
No, you aren't being too sensitive. A power exchange relationship isn't an invitation to be a jerk. (Unless jerkiness - insensitivity - has been specified in advance.)
Some people aren't good at friendships in either vanilla or kink life. And the top in question may not have how you are to be treated clear in her own mind.