Volunteering your own relationship troubles to show solidarity is one thing, but the problem with spreading negatives about is that one can't call them back in. If you wanted this to remain secret you shouldn't have shared it. Was this to be only between you and your boyfriend? If so, then you can't complain about broken trust when you broke trust. If not, those are long term consequences of his actions coming home to roost.

But spreading this information around, you do invite past problems back. You apparently moved past this issue with him, or should have. Revisiting it with other people well after the fact doesn't do many favors there. It's tedious to have to work through the same problem more than once.