In the world of metaphors where the rain and clouds are gloom and doom, the swords are the truth or knowledge, and the heart is a heart-shaped heart, the THREE of SWORDS is pretty literal. The heart is pierced and and betrayed by the truth, and nobody is happy about it.
This is a time to face and acknowledge what is really happening. Up until now the reality of the situation has been avoided, hidden, or denied, and now there is no where to be but present with it.
The good news about this card is it is not actually literal. Our real hearts cannot actually be broken or stabbed by knowledge, however painful it may feel to learn something upsetting. In moments like these, it's helpful to try to see what is what. What is the truth? What is the feeling? And what are the stories we are adding to the truth?
It is important to be honest with ourselves when we are pulling this card. Is it our hearts that are being pierced? Or is it us doing the stabbing, and potentially hurting someone else?