Having an agreement is one thing. Threatening to sue and blackmailing with invalid immigration-related claims is quite another. I don't believe the former partner has a case for anything, but if there is any claim, it would be for breach of contract, not theft. Certainly nothing that would land either a conviction or a permanent visa denial. This is a scare tactic, not a pursuit of a claim. It sounds like the two had both committed to work on the company, but only one really did and he now feels used. Obviously we only have one side of the story, but from the available data it seems it was not the OP who broke the original commitment to the company.

Also, how the hell is he screwing his countrymen, as you claim? Are you saying that because someone got screwed by someone in country X, noone will want to do business with other people from country X anymore? That makes no sense.