I tend to feel better when those close to me know what's going on w/ me. Especially if my ostomy might somehow "show itself" to them, like if it's making lots of noise or I have to change the bag often.
It helps me feel less anxious about things. I just put it out there so I am not so self conscious and not spending so much time worrying about what's happening w/ my ostomy. I can relax.
And I also feel like if people are better educated and understand ostomies, they are less likely to judge. Of course, they may be curious so I usually tell people to ask questions if they want to know something. I feel like people won't sit there wondering what's going on if I'm open about it.
Maybe even talk to the one person who does know and tell him how you feel about it and see what he thinks.
I would encourage you to think about what you might want to say if the subject comes up. Again, it might help decrease any anxiety you are feeling just to have an idea of what you would want to share.
Just my experiences though. Like others said, everyone has different things that work for them.
Have a great time!!