Your dream is rich with symbolism and can be interpreted in several ways. Here are some insights into the various elements:

1. Driving and Loss of Control: Driving often represents your journey in life and how you navigate your experiences. The chaotic scene on the highway may reflect feelings of anxiety or a lack of control in your waking life. The hydroplaning and accidents symbolize unexpected challenges or events that disrupt your path.
2. The Big Rig Truck: Being hit by a big rig could signify a significant impact or realization that has struck you emotionally. This might relate to an overwhelming situation or a decision that feels too heavy or out of your control.
3. Family and Community Gathering: The presence of family and community could represent your support system. However, the gray shadowy figures suggest feelings of disconnection or unresolved issues, possibly indicating that you feel overlooked or unheard in your relationships.
4. Realization of Being Deceased: The moment you realize you are part of the accident reflects a confrontation with a personal truth or fear, perhaps about mortality, significant change, or loss. It may also represent a feeling of being trapped in a situation or emotion that you cannot escape.
5. Memorial and Acceptance: The memorial signifies remembrance and acknowledgment of past events or relationships. Your agreement to stay with your cousin and sister, despite realizing your fate, indicates a desire for connection and support, even in difficult times. It suggests a process of acceptance, both of your feelings and perhaps of the changes in your life.

Advice:

• Reflect on Control: Consider areas in your life where you feel a lack of control. It might be helpful to identify these aspects and think about how you can regain a sense of agency.
• Connect with Others: Reach out to your support network. Sharing your feelings with trusted friends or family can help alleviate feelings of isolation.
• Process Emotions: Allow yourself to process any unresolved emotions related to loss or significant changes. Journaling or speaking with a counselor may provide clarity and healing.

This dream serves as a profound reminder of your emotional landscape and the importance of connection and acknowledgment in navigating life's challenges.