Guy I work with

Sure why not? If you like him and not your boyfriend and this is same for him too. Being the boss or being at work should not change much. If you think it does then you don't like him that much anyway so just don't screw everything.
As long as YOU think it's worth it, then yes you should pursue him(of course it should be mutual).

First I would be honest and brake it off with the guy you are involved with now because that's only fair.. BUT I would also make sure they guy you are sleeping with feels the same way you feel because he could just be wanting to have sex with you if you both are on the same page go for it!!

Mixing business with pleasure is not a good idea. You both are each hurting the one's your in a relationship with. Imagine if they were cheating with one another and you guys didn't know. How would you feel? I'm in a relationship and I think that's so wrong to just up and cheat. Don't leave the one you love for the one you like. The one you like may leave you for the one they love.

You can not have both. Chose. Sometimes when we are in relationships the person we are with is not the person for us. The fact that you already cheated on your partner should tell you something.

Hmmmm... kind of conflict of interests here, huh? I mean if you like him it should be ok right? But you work together. Not only work together but you are his boss. What happens if you break up? You'll have to see him every day and just after a break up it may be difficult. Things may get too bad and he could get fired, not saying you'll do that but it could happen.

On another note, you said you were both in relationships? You had sex with this man and you are still in a relationship? Girl, that just ain't right, I mean it's ok if you fall out of love with someone but it's never ok to do that to somebody. NEVER. that can kill people inside. You should have broken up with your boyfriend before you even thought about having sex with somebody else, even if you don't love your boyfriend. And what happens if you break up with your boyfriend to date that other guy and he says he wants to be with his girlfriend instead, and then you lose two relationships right there. You should really think about this long and hard before you make any other decisions about this thing you've got going on.

It is NEVER a good idea to "fish off the company pier". If you guys date and you break up, you still have to work together. It is also NEVER a good idea to date someone who you supervise at work, there are all kinds of major ethics issues there, too.