Reflections and solutions to my conflict

Firstly I would wish to thank everyone who commented. As the conflict had already occurred, I am able to with you guys the outcome.
At the end of the day, the team managed to persuade Crystale not to send out the “poison pen” email. However, Crystale felt that the final act of blame shifting by Jana was the last straw. As a result, Crystale resigned from the company 2 weeks after receiving the warning letter. To add insult to injury, the company refused to issue Crystale with a letter of recommendation or testimonial.
On the bright side, Jana misdeeds did not go unnoticed. Management finally decided to act and Jana was asked to leave the company 1 month after the incident.
Personally, I felt that I had done all that I could. As Crystale was rather stubborn in nature, it was considered a miracle that the team even managed to persuade her into not sending the “poison pen” email. I believe this incident has really opened my eyes to the true nature of the workplace.