It's clear that a number of people posting in this thread do not understand how the legal system in the US works. We will not get additional details because Dubina made a plea deal. A criminal trial would have made more evidence public, but he (presumably with advice from his lawyers) made the decision that a trial would be worse than pleading guilty and serving 60 days in jail, etc.
From this, we can infer that the process and potential outcomes of a trial would have been risky or damaging for Dubina. One reason to avoid a trial could be the risk of becoming a registered sex offender if found guilty of the sexual imposition charge. Another reason is that he might want to prevent details/evidence of the crime (and we can say it was a crime -- by definition since he's plead guilty) from coming to light in a trial.
So while the details of the crime remain unknown (outside of those close to the situation who may understandably want to protect their privacy), that does not mean we don't know anything about the severity of the crime he committed. If Dubina wanted those details to be made public, he only needed to go to trial. The fact that he chose a certain jail sentence over that outcome is revealing in itself.