Dear faber castell:

I would write to her a short message, something authentic that comes from you. Here is what comes to my mind, but of course, it has to be YOUR own:

I would write something like this: “I cared for you a lot and I believe that you were often not honest with me. It hurt me that you were not honest with me as often as you were. I wish you spoke your mind and told me how it really was for you, then we could have, I would hope, helped each other and loved each other. But being honest, straightforward, direct with me.. these were not your choices. It saddens me. And so, sadly, it is my choice to end our relationship.

(name)

This way you are giving her your honesty (yet again, for the final time, as is) and you are giving her a gift, an opportunity to examine herself. You are letting her experience the CONSEQUENCE of her dishonesty with you, the natural consequence. this is the best you can do, says I.

anita