I don't think it is necessarily a bad thing to be sensitive...I think you are confusing this term "over emotional" with sensitive. I am sensitive too-I am very empathetic, I feel people's pain very easily and I want to help them. Sometimes, however, my boundaries get lost and I feel depleted because I take on other people's baggage...

Sensitivity and emotionality are good qualities to have during these difficult times-in our modernized world, where sometimes it feels like very little people seem to want to feel anything and quick fixes are abundant to escape our realities.

You make it sound like there is something wrong with you being this way and there isn't. I would love to have a friend like you who would feel sad if I cry. (and hey, I cry at the show BBC's Planet Earth just for the sheer glory of how beautiful and miraculous our world and nature is).

Sounds to me like you are doing a great job at keeping your boundaries with your coworker. Give your sensitivity to people who replenish you and give back. Then you wont feel overwhelmed.