Since 2007, I have attended 10-day Buddhist meditation retreats which have helped me significantly. A chance remark by a friend helped me realize that the meditation technique taught at these retreats is actually a 1-person technique for opening up! I was fascinated to see meditation that way :) Let me explain.
The first technique taught in the 10-day meditation retreats is Breath Meditation: we learn to pay attention to unmodified breath in the nose region for long periods of time, without getting distracted. This practice develops 'awareness' (we become adept at paying attention to subtle bodily phenomena like breath and body sensations). It also develops 'one-pointedness' (we don't get distracted easily) and 'tranquility' (we become calm).
After practicing Breath Meditation for a few days, we are taught taught Insight Meditation (also known as 'Vipassana Meditation'). In this practice, we scan our body from head to toe, slowly, focusing on sensations that arise on the surface of the body (the body scan techniques are quite detailed and intricate; only a good teacher can describe them well). With each sensation that we encounter, we make sure that we don't react with craving or aversion. Some sensations are unpleasant which trigger a response full of aversion. Sometimes, we miss pleasant sensations that we experienced in the past and we trigger craving for them. The key ingredient of Insight Mediation is to stay away from both craving and aversion. This way, we become 'equanimous' (balanced, even, level).
At the meditation retreat, we are encouraged to notice within ourselves that our mind works sequentially as follows:
Cognition: we see something, we hear something, we smell something, we feel something, we taste something or we think something; so it's the five senses and the thought process).
Recognition: we remember that what we just cognized has happened in the past.
Sensation: after recognition, a sensation arises somewhere in the body (not limited to the surface of the body but anywhere).
Reaction: this is our response to the sensation.
The above four steps (cognition, recognition, sensation and reaction) occur repeatedly and so quickly that we don't notice them in our day to day life. With practice, we can train ourselves to start noticing these mental phenomena in ourselves.
At the meditation retreat, we are taught that we can't influence the first three steps (cognition, recognition and sensations). However, we can train our mind to react differently from how we have been reacting in the past to similar sensations. That's the key to healing. We are encouraged to notice that our misery (negative feelings characterized by anger, hatred, ill-will, fear and so on) is a function of our reaction, nothing else: if we react with craving for a pleasant sensation that is no longer available, or if we react with aversion to an unpleasant sensation that is occurring right now, we become miserable. On the other hand, if we react with equanimity (characterized by positive emotions like joy, love, kindness and so on), we are calm and peaceful.
When we start meditating (Breath Meditation or Insight Meditation), thoughts associated with some trauma from the past become strong. Quickly, we start feeling unpleasant sensations in our body. Thoughts and sensations associated with that trauma start manifesting themselves like an avalanche. We try our best to practice equanimity, thereby changing our reaction to these sensations. In some sense, we relive the past, just like in a psychotherapy session, or a hypnotherapy session, or when we were journaling or talking to a confidant.
Thus the overall process of healing through meditation is the same as opening up. However, it is a 1-person system in which we play the roles of both the narrator and the listener :)