Perhaps that was because he believed that she was withdrawing her allegations based upon her concern that you would be fired, not because they were false, and he didn't appreciate your attempting to repay her gift to you by getting her fired.
When an employee is repeatedly accused of sexual harassment, it's not unreasonable for a company to protect itself by terminating the employee. Unless you have an actual employment contract that requires some level of due process, a collective bargaining agreement (union contract) or civil service protections, the employer doesn't have to be fair about it. They can fire you simply for being accused, even if it's the first time.Quoting j_olivier
They don't have to confirm your positions. They have the legal right to decline to give references and to ignore requests for information from your prospective employers.Quoting j_olivier
Getting fired is stressful, and it can be worse when combined with stress from other unfortunate events in your life. But that does not mean you get to sue your employer -- statute of limitations issues aside, so far you haven't given us any basis to conclude that the termination was wrongful.Quoting j_olivier
To the extent that you have not done so, you can report their H1-B visa improprieties to the Department of Labor.

