My biggest fear at the moment is that they will turn around in the future and try to take action against me. If they are telling others that they wrote the code, and if someone tells them about my code, i wouldn't want to face a legal battle. Maybe it's unfounded, but I'm still a bit emotional.
If they were just using the software and telling investors that they were using it under the Apache license, there would be no problem. The investor said that the startup is claiming they actually wrote the code.