It sounds like your dream is a reflection of unresolved feelings related to your past relationship and the way it ended. Nightmares about an ex, especially in a scenario where they invade your space and refuse to leave, can symbolize feelings of being trapped or overwhelmed by unresolved emotions.

Your ex's uninvited presence in your dreams may represent lingering thoughts or feelings of anger, betrayal, or even a sense of violation regarding how the relationship ended. The act of screaming for him to leave could signify your desire to assert your boundaries and reclaim your personal space, which may feel threatened by these memories.

It’s possible that these nightmares are prompting you to confront the emotions tied to this experience and to process any lingering trauma. Consider reflecting on what specific feelings arise during these dreams and how they relate to your waking life.

Here are a few steps you might take to help address these dreams:

1. Journaling: Write down your feelings about the relationship and the breakup. This can help you process your emotions.
2. Therapy: If these dreams continue to disturb you, speaking with a professional might help you work through any unresolved trauma.
3. Setting Intentions: Before going to bed, you might try setting an intention for peaceful dreams or visualizing a safe space where you can feel secure.

Remember that dreams often serve as a way for our subconscious to process experiences, so addressing the underlying emotions may help alleviate the nightmares.