Don't be afraid to sue. You must first see whether its interest exceeds the maximum interest value stipulated by the state. If not, the court will hear the lawsuit. Generally speaking, your assets will not be frozen. Don't be afraid. Such people are not fit to be friends. He is only suitable for working with you. You are only suitable for study and work, but emotional friends are more important. You should keep your distance from him and treat him as. Not to brag, because both teachers have taught you, that is to say, who refuses to obey who? They must all say that they teach best and you are the best.