Hi LucyLou, I can relate to this. I've battled SH for years. I also have an excellent trauma therapist. I've told him about it, and he understands that it's a coping mechanism and not an attempt at suicide. Not all therapists understand that, and it might be best to talk to your therapist and ask about it. You could bring up the past SH and say that it's been on your mind since Tuesday and ask what she thinks about it all. That would help take the pressure off of you worrying about how she would react if you told her what you did. It might also open up discussion about it that might help.
I also have so much trouble talking about the trauma. It's so hard to get the words out. I'm fortunate to have a therapist that understands this and also knows that it takes time. How much time? It takes as long as it takes, and we're all different.
For years I've looked at SH as the worst coping mechanism and tried to avoid it. Then I'd tell myself, "Why does this have to be the worst, why do I have to try to not do this? Is it because society doesn't understand it and thinks it's horrific?" I was able to give myself some space over it and realized that if I do it, then I do it. I try not to, and as I said I struggle with it. But, it's just a coping mechanism. And as time goes on and I work on it more, I can lean more and more on the healthier coping mechanisms.