It is very possible you gave it to them. The previous post is incorrect. It IS possible to spread WITHOUT any visible symptoms. Less likely, true, but still possible.
You MUST use a condom EVERY time, no excuses!
If you are a man and just don't like using condoms try using different brands. I've found using Trojan UltraThin lubricated is pretty darn close to wearing nothing at all.
Besides, you have no idea what the other people could have, just as they had no idea you have herpes. Best to be protected both ways just in case. The small increase in pleasure from not using a condom is not worth the risk of contracting HIV.