Depends how much of a "free spirit" you feel yourself to be. If you're in an open relationship (which by its nature is hedging against commitment) go with your heart.
The only problem is relationships at work. So many potential problems. Were you to get physically involved and the whole workplace knew it would be difficult to undo without turning sour...possibly even prompting one of you to leave. Then again, what's his attitude toward women? If "he seduced you" or you him, how would his behaviour change toward you? Would he try to dominate/control your interactions at work.
As you say (and rightly admit) you're infatuated. So don't inadvertently tread in a mess! Empath you may be but be sure you've got it right. It's very chancy when you're romantically swept off your feet - a temptation to project your emotions onto someone and see the reflection through rose-coloured specs...
But then, if you're ok with all these things, go with the flow. At least you'll get it off your chest, so to speak. If you're in an open relationship there's a tacit understanding is that it isn't permanent anyway. I think you should explain to your situation to the guy (at work) at the earliest chance
if you date, so you don't mislead him. Who knows? He might be in the same thing.
Then you must evaluate where your current relationship is at. What would it cost you emotion-wise?
A bit of a trade-off to ponder over Christmas
And may it be a merry one!