From reading your explanation, code of ethics was violated and that from everything that has happen as this is in the past and time to recover and rethink what was done. I am sure you feel terrible over what had happen and that you would take that night back in a second if you could. This is where though you can rebuild your trust with a new employer and show that you have the professional manner in which to be hired no matter the past.
Honesty is important as any background check will discover what happen at your previous employer. No need to be specific in what events happen that night but if asked, explain that poor judgement was made and that you have learned from your mistake and that you want a chance to be a productive part of the new company you are interviewing with.
The interview should then turn toward your talents and professional work ethic and less toward the incident that happen in the past. Let the interviewer again know that you have learned from your mistake and that you are willing to start new with this company and to have a position to grow and start from the bottom up. Only way I believe that you can be given a chance as I would hope a prospective company will give you that chance.
I hope that this information was found helpful as I wish you the best in the interview process. Please let me know of any additional questions/concerns you might have as well as also if you could take a second to rate my assistance so that i know my help was found useful today.
Best of luck,