Your question/statements are a little confusing and ambiguous.
Separating from the current spouse with whom you are in an irregular marriage? Yes.
Reconciling with the first spouse? Yes
But, many times it is not possible to reconcile with the first, nor desirable.
And, moreover, most times the couple in question wants to convalidate their current marriage not break up permanently.
If there are children involved, the Church does not ask the couple to separate during the time when they are waiting for a decree of nullity or other resolution to their situation so that they can convalidate the marriage. The remedy would be continence (i.e. “living as brother and sister”) but that could be done under the same roof for the sake of children involved.
However, all of the above is merely in the abstract.
This is really something that should **only **be undertaken under the guidance of **your **pastor. Go talk to your pastor and lay out all the facts of your **specific **situation, tell him of your desire to resume the sacraments, and he will guide you as to what is necessary.