Getting Past The Past: How To Start A New Relationship Without the Old Baggage

When a relationship ends we need to allow a period of reflection, even grieving, before beginning a new one.  But when the painful emotional wounds from the relationship have not healed, we bring fear of a repeat of pain with us into a potential new relationship. We may overreact to every little thing, arguing over every difference in opinion or misunderstanding, constantly on the defense and threatening to end the relationship before it even takes root. We attempt to shield oursselves from hurt, and as a result our repeated failed relationships become self fulfilling prophesies.  We may fear rejection because of some fault or past mistake that may have been the cause of the previous breakup. How do we get past the past and start a new relationship without bringing baggage?