Elder Zacharias of Essex was asked by a priest, "Where is the heart? The elder answered, "The heart is within our chest. When we speak of the heart we speak of the spiritual heart, which coincides with the fleshly one; but when man receives illumination and sanctification, then his whole being becomes a heart. The heart is synonymous with the soul, with the spirit; it is a spiritual place where a man finds his unity; where his mind is enthroned when he has been healed of the passions." (From: "Hidden man of the heart'")
I believe purgatory's purpose is not punishment, but is designed to make us all heart, finishing a process we had entered into but have not finished. To be all heart is to be in the likeness of God. So many will not accept humility, giving very little space to love. Purgatory humbles, so love can take over all the space in our heart (soul). Then there will be space there even for those who were our enemy in life. Isn't now the time humility should be our quest - so when we die we are already all heart?