I think it is a little of both. It is usually reliable because it was a memory so painful it has to be repressed but if the memory is not delt with in a healthy manner then it becomes hurtful in my opinion.
You have no idea how hurtful they are, but then again you may have an idea.
I would say both. Some have been “brokenhearted” for reasons that others find difficult to understand. For example there are adults who, on the basis of what have been described as “repressed memories,” say that they were sexually abused when they were children. Some have no thought of having been molested until, unexpectedly, they experience flashbacks and “memories” of an adult (or adults) abusing them when they were young. Often the basic goals of therapy are: To recognize and accept one’s own feelings (to overcome negative feelings you must first face them); to understand the feelings of the other person and how one’s actions affect him or her emotionally; and to apply this insight, thus learning how best to act.