As far as your friend has evidents that the prosessor seduced her, she can sue both the professor and the university. She will have a good chance to win. There are quite some attorneys free at the beginning and will only take a percentage cut when they win the cases. Just call around and find out a good attorney. In the meaning time, tell your friend to keep a valid visa status. There are many ways to do that. Just ask around.
Big cat probably give you much better advices on which leg choices your friend has.