old friends

I had some drinks with a friend and she wanted to go to another friends to see him. I went with her so she didn't do anything that she would regret. But the place we went to was at an old friend of mine and my boyfriend doesn't like him. We used to have a bit of history and I don't know what to do, nothing happened between us but I feel horrible for not  telling my boyfriend. What should I do. 😞😞