Living with a broken heart is a special kind of insanity. From a Zen practice perspective it provides a unique opportunity to kick your ego while its down. You can dive into the abyss of sadness and suffering and look intensely for its cause. You can explore attachment and self. You can immerse yourself in meditation like nothing else matters. For most people though, the sadness and depression that follows the end of a significant relationship is a normal and expected part of the grieving process. It is not classified as insanity, because it is a reasonable response to a major life change.
Without shaving your head and joining a monastery, you can use your broken heart to grow through the suffering and come to a better understanding of love and yourself. You can use a mindfulness practice of compassionate breathing to help you through the hardest hours. You can salvage the love from the wreckage of the relationship and use it like a bandage to dress your wounds. You can even meditate like nothing else matters.
If you want to heal your immediate suffering, but not all the suffering of all time, you don’t have to do anything as extreme as meditating. You can just watch your thoughts and practice compassion. You can think about the stages of grieving to categorize your thoughts and remind yourself that your thoughts are reasonable thoughts. The stages of grieving are denial, bargaining, anger, depression, and acceptance. In grief you generally jump around theses stages rather than progress through them. If you think about getting back together, that is a mix of bargaining and denial. If you think about how you could have done something differently, that is bargaining again. If you just cry, that is depression. If you make lists of what the other person did wrong, that is anger. When you stop thinking these kinds of things, that is acceptance. When you notice yourself thinking, you can see what your thoughts are and let them go. Remember you are grieving and take a breath of the pure love that inspired your suffering. Remind yourself that you can love and be loved. Breathe out love for the other person who is suffering too.
Whether you are a Zen practitioner or not, a broken heart is a unique time of growth. You are forced into a process of reorganizing yourself. If you organize yourself with kindness and compassion, your heart will mend beautifully.