Dreams often reflect our subconscious thoughts, emotions, and experiences, and yours seems to be rich with complex themes. Here are some possible interpretations for your dream:

1. Hiding and Conflict: Hiding behind the car could symbolize feelings of vulnerability or a desire to avoid confrontation. Your husband's friend and wife, whom you do not like, may represent external pressures or conflicts in your life that you are trying to escape.
2. Family Dynamics: The presence of your stepson and step-siblings suggests unresolved feelings about family relationships. Your stepson being mean to you could indicate feelings of rejection or conflict within your blended family. It may also reflect your worries about how your family is functioning or your role within it.
3. Separation from Your Husband: Climbing the stairs to get into the house might symbolize your desire to reconnect with your husband, especially since you mentioned being separated. Stairs can represent progress or transitions, indicating your desire to move forward in your relationship.
4. Childhood Influences: The appearance of your step-sister, who was mean to you in the past, could indicate that old wounds or feelings of inadequacy are resurfacing. This might relate to how you feel about your current family dynamics or unresolved issues from your childhood.
5. Concern for Your Daughter: Your daughter crying and saying that your stepson hit her reflects your protective instincts. It might symbolize your fears about her safety and well-being within your family environment.

Overall, this dream may be calling your attention to unresolved family issues, feelings of vulnerability, and your desire for harmony. It could be beneficial to reflect on your current relationships and consider open communication with your husband and family members to address any underlying tensions.