Anxiety is not a legitimate excuse for abuse, as there is no excuse for abuse.

However, it can contribute to heightening the abuser's emotions. For example, say someone has an anxiety about you leaving him. He would react by becoming more controlling or threatening.

Or he may have a general fear of abandonment, or be paranoid about people because he can't trust anyone. There may be some events that trigger his emotions, which he may not have the skills to regulate.

Again, I am not excusing him for his behavior; just trying to figure out some possibilities.