I have been back stabbed, ignored, and treated completely wrong with my past partners. They traded my for someone who I think was of lesser skill and wasn't as committed as I. I was not even told I had to figure it out myself. I can tell you it hurt really bad when I found out and I would have felt better if he had told me earlier on. I would say to do things in person and show that you are truly sorry and if there is anything you can do to make it up. Maybe practice with her twice a month or do social dancing together. Then she won't feel like you are totally leaving her, and then you can slow stop practicing with her. It makes it better and you will feel better about it. Trust me I found out and I was furious with my partner. I talked to him and I made him cry. I don't know how your partnership is but ours was very strong and we were good friends. I mean if you don't want to cry take it slow.

I hope this helps!

~Me