You should not feel guilty if you did nothing wrong. You may be feeling as though you did something wrong because your ex has trust and jealousy issues.
I would need much more information to determine if your feelings of guilt are warranted. For instance, it would be helpful to know how long you and your ex had been together before the breakup. It would also be helpful to know what led to the breakup, how long you and he had been apart at the time you went to the bar, and what the exact nature of your relationship was at the time of the incident.
You stated that you had broken up with your boyfriend. It would seem that if you two were no longer together, then you did nothing wrong.
If you would like to write back and provide additional information about the relationship, and provide a rationale for why you believe that you may have done something wrong, I may be able to provide you with a more direct answer to your question. Please take care.
Dr. Kristina Randle