Project with no contract

Hi there, ask lang po nmin sa mga kagalang galang ng lawyers dito. Software developers po ako, i have an office work, then by week ends and free time i do sideline/freelance making web and apps. Then this client ask for our help as need na nila mag comply sa main client nila, development timeframe should atleast 1month sana, ang nangyari naging 2weeks, creating 3 apps. halos d ako natutulog to comply and nagkasakit pko. We have no contract and scope - everything is verbal, and to the point na they want something i didnt agree with such as the source code (as i know source code is beyond intellectual property rights). The output is delivered and main client is using it (though may minor change n gusto si main client) by which its not even the app standards. I said give time for RnD, but they are stuborn and want it ura-urada. I said i quit. 50% paid lang rin sya.

On my end, i just gonna let it go and move on, pero makulet itong si client. naghahabol pa... how can i counter this.

Many thanks