Investor Wants to Replace My Co-Founder. Need Advice!

Throwaway account for anonymity.
My co-founder (CF1) and I run a real estate PropTech startup. An investor verbally committed ₹6 Cr but delayed closing for a month, causing internal friction. CF1 briefly left group chats over frustration. Now, the investor wants to replace CF1 with a “new co-founder” and will decide this weekend.

CF1 is critical to operations (IIM grad | 10+ years in real estate). How do I:

1. Convince the investor to retain CF1?
2. Navigate this without losing funding?
3. Prepare alternatives if the deal falls through?

Hyderabad-based. Any advice appreciated!*