Some men are sexually aggressive because they are basically insecure. Forcing sex on another person makes them feel strong because it makes someone else feel weak. Rape is violence against a woman. It is an issue that strikes at the heart of the personal relationship between a man and a woman, how they treat each other, and how they respect each other's wishes. People who respect others do not coerce others to do things they do not want to do.
Men can be victims of rape and have the same rights to counseling and legal action as women do.
Stay calm and think. Figure out what your options are and how safe it is to resist. This is rape. This might shock the rapist into stopping. Assess the situation.