You have been scammed.

Leave immediately, take your IP, and don't even consider doing anything else until things are in writing and the backpay, etc are resolved.

I would go a step further and get the hell away from these guys. If they've scammed you, they've likely scammed others and/or will scam people again. This could be you again, customers, or your investors. You do NOT want to be part of a team that scams their investors.

Walk.