You might have a hidden diamond for team collaboration here, but after reading more than most potential customers will, I'm not sure exactly what it is.
I'm not a fan of the to-do/chat combination. There just isn't a lot of intersection between the things on my to-do list and the things I want to chat about. Who wants to chat about their grocery list? Who would contact their family about dinner plans with this instead of a phone call, text message, Tweet, etc. just because they can easily save a to-do item? Perhaps this has other uses.
Consider extremely detailed user stories. Who might want to this? A software product manager communicating with the technical team about features and bugs; a high-school student and her study group; an extended family planning a vacation together?
What would they share, and how does this tool help? Why would they use something new instead of a phone, e-mail, Twitter, Facebook, preferred existing group to-do list app, or a thousand other tools? What are their favorite colors; favorite words; turn-offs?
Kudos on what you've done so far. And remember, even if this fails as a startup (most do), it certainly demonstrates your skills. Hopefully it will open doors.
Oh...and don't bankrupt yourself working on this. That would just be crazy.