We don't have to tell our partners everything

We don't have to tell our partners everything, LIL. Sometimes over-disclosure can imply that there's a problem when there isn't. If he's not interested in this woman and just enjoys catching up with her on occasion, he probably doesn't need to make a big confession about it. Old friends are OK. Not all exes are threats.
What's not OK is the double standard. Do you really have to tell him everything? Has he eased up on the jealousy over time? Because that will get old.
And ... how often is he talking to this woman? I can understand the occasional phone call, but is this ongoing? If she’s a close friend -- someone who's a big part of his life -- he's going to have to do a better job of bringing her into your shared world. If you're living together, you have to have a good sense of each other's communities. That's only fair.
But let's get to the last part of your letter, where you tell us that you want to be his support system. Forget about this woman for a second and ask yourself, "Are we getting closer? Does he confide in me? How is our friendship?" Those are the important questions. If you feel like things with Matt are getting better -- and more fun -- with time, none of the other stuff matters so much. If you're feeling alone in this relationship, it probably has nothing to do with this woman. It's about him. And you.
Focus on what's happening between the two of you. It's been a year now. It's time to ask yourself whether you're really happy and can relax in this relationship.
Readers? Should she be worried about this woman? What about the speed of this relationship? Do you get the sense that they're happy? At a year, how should the letter writer feel about things?