Forgot close friend’s birthday

I was having a friendsgiving and invited my close friend, and she told me she couldn’t come because it was her birthday. A few days later, something triggered me and a different part took control for several days (including the friendsgiving)- that part completely forgot my friend’s birthday. I feel like such a terrible person- my friend reminded me that she told me it was her birthday literally a few days previously, and I had been working on a gift for her. I told her that I have memory issues/a memory disorder, but I think she thought I was just using it as an excuse.

I apologized, but still feel terrible. And the gift wasn’t finished in time, because the part that took over didn’t know to work on it. My disorder is not something I tell people other than my therapist/psychiatrist about, but I’m considering fessing up so my friend knows I didn’t intentionally snub her. I just don’t know if I can trust people who don’t know what DID really is, or if she’ll start treating me like a freak.

I’m still working on finishing the gift because it’s handmade. This whole situation is so frustrating, and I’m worried there are things I was supposed to do that I was told to do as a different part that I am now forgetting to do…therefore continuing to mess things up.