You and the other developer basically built the product to the point where they're able to get real, actual money into the founder's hands. That alone demonstrates that you have great ability in what you do and getting it done successfully.
The way these founders are carrying out their actions is pre-planned. Everything you listed that they did was to protect and set themselves up to be the sole owner and reap all the benefits. And considering you're from another country, there is a huge chance they'll just rip you off or break their employment agreements with you whenever they want (probably including sketchy math when it comes to options payout/dilution). And you will have no recourse unless you want to wait years and pay for the legal costs that come with it.
You can test the waters too. See if they'll make you a full time employee, and get a title bump of CTO or something. Or if you think that's too much, get like Senior Architect or something that will look good on your resume for your next job. And ask for a real huge salary bump. If they say they can't do it, or can do it next year (ie putting it off), you'll know they're not serious about keeping you, which means they're already planning on screwing you at some point. As you said, you don't really believe their verbal promises, so bring up a real conversation with real tangible benefits to you and watch carefully how their poker face reacts. It'll tell you a lot.
But to be honest, I would plan to cash out and use your work time to find a different gig in the meantime. Scale back your deliveries and prep for interviews. Your skill level is likely high enough to work at a big named corp with great pay and benefits (ie Google and the like). Larger corps are a lot less likely to rip you off unlike startup founders because they generally have presence in the the country they're operating in and have to follow local laws. Good luck!