It is important to approach this situation with sensitivity, respect, and consideration for the well-being and emotions of all individuals involved. Here are a few things to consider:

1. Honesty and Communication: Open and honest communication is crucial. Sit down with your wife and have a heart-to-heart conversation about your feelings and thoughts regarding the situation. Express your concerns, fears, and desires openly, giving space for her to do the same.

2. Seeking Professional Help: Given the complexity of the situation, it might be beneficial for both you and your wife to seek professional guidance from a therapist or counselor. They can help you navigate and understand the dynamics at play, providing a safe space for open conversations.

3. Emotional Impact: Consider the emotional impact this situation may have on your wife and her mother. Pregnancy and the merging of relationships can cause significant emotional turmoil. It is important to prioritize the well-being of all parties involved and make decisions that foster a healthy and supportive environment for everyone.

4. Long-Term Considerations: Reflect on the long-term implications of your decisions. How might this unconventional arrangement impact the relationships within the family? How will it affect your marriage? It is essential to think about the future and determine if this situation aligns with your values, goals, and overall happiness.

Remember, this situation is unique and highly personal, which is why professional guidance is strongly recommended. Only by working through this complex dynamic together can you make an informed decision that respects and supports the well-being of everyone involved.