Hello,
This is my first post. But it caught my attention.
The part of struggling with feelings and regrets its normal. It seems that you made a clear decision, explaining everything to her, something that in my opinion is really good. However, you must understand that this was your decision, and if you’re having second thoughts and let her know, you will only make her have false hopes and hurt her more.
It’s normal to have this moments of life (I’m actually living it but from her perspective) and trust me, that it really hurts and everything that you tell her, text her, etc. she will over analyze it.
In other terms, my opinion as someone dealing with feelings from her perspective is try to avoid to tell her anything that may led her to think you will get back together unless you want to do it.
If you have any doubts about how she might be feeling, everyone is different, but I could try to describe it.
Good luck.