HI,
I do agree with you that you made a mistake in calling your ex, even though she was sick. All that did was to re-start feelings, and stop you from moving on for the time being.
I think you will be much better off, not communicating with her at all, and move on with this new girl. You have to, somehow, start moving on.
Letting go of the past is the only way you are going to be "free".
It will take awhile, but you can do it. Best of luck, and hang in there.