Keep in mind that, if you are a beginner who was taken on for a big project, then your client hired you to get a much cheaper deal than with an experienced deve

Keep in mind that, if you are a beginner who was taken on for a big project, then your client hired you to get a much cheaper deal than with an experienced developer, against the risk of a delayed or unfinished application. If it doesn't work out and he makes a loss, tough - it was his decision to take that risk in the first place. And it sounds like he repeatedly extended the scope of the project without offering additional compensation, which is very dishonest. If you can't finish the job, don't. And don't let the client guilt-trip you: you're not responsible for his losses, he is. If you can't deliver, then the worst that can happen is for you to return the payment already received. At this stage, stop working, cut off all direct communication, and hire a lawyer. And stop worrying - we have all had a failed project or two in our careers.