Dreams about weddings, especially those involving former coworkers or acquaintances, can often symbolize changes, unions, or significant transitions in your life or the lives of those involved. Here are some interpretations based on the details of your dream:

1. Reflection on Relationships: Your dream may be prompting you to reflect on your own views about relationships and partnerships. The fact that you were shocked by the choice of partner could indicate your feelings or judgments about compatibility and suitability in relationships.
2. Concerns for Others: The dream could also reflect your concern for your former coworker. If you feel that the new partner is not a good match, it might signify worries about your coworker’s well-being or choices in life.
3. Processing Past Experiences: The mention of his ex being hurtful and abusive might suggest that you are processing past experiences, either yours or those of others. It could indicate a desire to see people heal from past relationships and make better choices moving forward.
4. Personal Growth and Change: Weddings often symbolize new beginnings. If your coworker is experiencing a change in his life, it could parallel your own journey of growth and transformation. It might be a reminder to evaluate your own relationships and the dynamics within them.
5. Emotional Insight: Finally, the dream could be a way for your subconscious to express feelings about commitment and trust. Consider how these themes resonate with your own life and experiences.

Reflecting on these aspects can help you understand any underlying messages your dream may hold. It can also be beneficial to think about how the dream made you feel, as emotions can provide further insight into its meaning.