Start with small things and work up to larger ones depending on how she responds to the small ones.

Take a chance with something you know you can recover from if, for some reason, your T doesn't understand or gets it wrong, etc.

Write down 8-10 individual things you feel you would like to tell her and then rank order them according to how hard they feel they would be to tell her and start with the easiest and think of an incident that illustrates it, etc. Then tell it as a little story and simply tell her at the beginning or end of the story that you find/found it difficult to tell her the story because it seem(ed) so hard/scary or whatever.