https://www.soundimmigration.com/i-864-enforcement/
If this does not scare you, well it should.
USCIS are not going to be interested unless you have SOLID evidence of immigration fraud, not marital issues.
I agree with the others divorce asap.
Paying for someone's education in the US suggests they must be pretty wealthy, we all know it is not cheap.
The Singapore guy, well it is 90 days and not $500, but please let us know how it goes when he try to reset his passport.