Hi Jessica...
wow, you've got a lot of history with her, your feelings must cut very deep here. i hope I don't say anything untoward... feel free to ignore if I'm not helpful. (forgive any typoes, I'm having trouble with my keyboard.)

she's thirty years older than you? that's a lot... my husband was thirteen years older than me, and i know that age isn't always as important as the rest of the world thinks it is, but sometimes it can be important. Is it possible that, with that kind of an age gap, your relationship was based on a family dynamic of some sort? that she was in some sense mothering you, and that at that time in your life you needed that kind of care? You say that she's controlling, who is more controlling in your life ever than your mother or father... as small children they control everything, what you eat, where and when you sleep, what clothes you wear. Maybe ten years ago you needed the safety of that kind of relationship, and she was good for you. Maybe she needed to mother someone, and you were good for her.

But if you have changed, that is if you've become more confident in yourself as you've "grown up" so to speak, she may see this as a threat. she can't mother you anymore, so she's resorting to smothering you instead. perhaps she can't help it, but her irrational behaviour recently might be her way of trying to assert control. What better way to make you feel weak and dependant than persuading you that you have a mental health problem like DID? I'm not saying she's doing it deliberately, but she's doing it for a reason. Perhaps her desire to keep you close is the issue. Perhaps she's aware that your intimacy has changed (because of her drug addiction it would seem) and that's why she has to get high to be with you. She's frightened because your relationship is evolving. All relationships do, and it's quite possible for them to survive transitional periods, but for whatever reason she sees change as destruction... she thinks things are changing for the worse, so her defenses kick in and she starts to be manipulative. This must be very scary for you... and believe me, I know I could be way out of line, but does any of this sound likely to you?

I take it your daughter is pretty grown up... you've been with your partner for ten years, your daughter was born before then?

Who in "real life" do you have to talk to? I'm really glad that you journal. It really helps.