As another member of the forum (long AWOL) used to say.
"All healing is done in the present. What we change is our perception of what is past."
Healing doesn't require that we change past events but it does cause us to change our view of what happend. That happens in the present.
If we actually sent energy into the past we would effectively change the past. Changing the past would change the present. We would not be where we are today (or possibly even here at all) because we would have been led to another future. If the past were changed we wouldn't have brought the issues associated with it into the present.
Walk in beauty,
Rebecca