Dreaming about conflicts with your ex-girlfriend's new partner, especially someone you feel has wronged you, can reflect unresolved feelings and emotions related to that past relationship. This type of dream often signifies:

1. Unresolved Anger or Resentment: You might still be processing emotions regarding the breakup and the circumstances surrounding it. The fight may symbolize your struggle to come to terms with your feelings of betrayal.
2. Fear of Confrontation: The dream could indicate an inner conflict where you're grappling with feelings of inadequacy or fear of being hurt again. It might represent a desire to stand up for yourself in situations where you felt powerless.
3. Need for Closure: This dream scenario suggests a need to confront and resolve past issues. It may be your subconscious prompting you to find closure with this chapter of your life.
4. Protective Instincts: If you still care about your ex or feel a sense of protectiveness towards her, the dream might reflect a desire to defend what you once valued.

To gain clarity, consider journaling about your feelings regarding this past relationship. It may also be beneficial to engage in activities that promote emotional healing, such as talking to friends or seeking support from a counselor.