The issue here seems to be one of a lack of trust. You may or may not have forgiven the one with whom you were in a relationship for the 5 years. Even if you have completely forgiven, you still may lack trust and this is not a sign of unforgiveness. It is a sign that you know hurt is possible when you commit to others. Forgiveness can help with taking the risk and at the same time your using common sense in the new relationship, along with sincere acts of trustworthiness by the other, should help to slowly create a trust with the new person.