What's done is done. You two broke up some time ago. What you did before you started studying is old news and is no one's business. The elder said it himself, what you did before you came to learn the "truth" is in the past. As long as you remain chaste since learning the "truth" that's the important thing (if you accept JWism)
So your ex-bf is a JW who broke some rules. Lesson learned: not all people who claim to be rigtheous are. But can you force people to be righteous by squealing to the elders everytime you see someone not being righteous?
Don't worry about your ex relationships. Worry about yourself and the path that you take. As long as your satisfied with what you are doing and where you are going that should keep you content and happy.
But before you get baptized in this religion, please do some research on in. Look past their own publications into the history of the religion, the scandals of the organization and their false prophecies. Can it stand up to scrutiny from outside their own world?
No one can tell you what to do, you have to decide what is best for you. But when you make that decision, please make sure that you have a firm understanding of what you are getting into before its too late to turn back.