Not sure if it is love, or delusion

[thelost]

I think I have serious feelings for my coworker, that I have been working with for the last year. We have a great connection and I just love spending time with him at work. We always laugh and flirt. However, he has a girlfriend and I am married. I am not really sure what I should do with our relationship. We of course never did anything provocative, we are just friends. However, I feel that with everyday that I see him, I fall in love with him more and more. It scares me and I don't know what to do about this situation. Should I quit my job, not see him, and try to forget all about him? Or should I continue this sweet torture that is leading me nowhere?

A little bit of background:
We have really similar tastes in books, food, and animals (we both love cats). During the summer he gave me his favorite books to read. He does everything I ask him to do (if I'd like some water or food, he goes to the store and gets it for me, if I need help with anything he helps me out). We have these cute play fights at work when we have down time (we work at night). This one time we were playing poker, and then just started throwing decks of cards at each other. Fly paper planes at work together. Watch scary movies at work together. And we always always smile at each other. We cannot look at each other without smiling. We also say naughty things to each other.

However, I only see him at work. His girlfriend does not allow him to be in my presence outside of work. We have only seen each other outside of work twice. Once I invited him to a climbing gym with me and after we climbed, we got some frozen yogurt, and work around in the dark alleys together. The next time we were at our coworkers party, and he brought his girlfriend with him. Ever since she saw me, she doesn't let him go anywhere with me. I was apparently to nice to him.

I really don't know, I am so confused about this situation. I don't even know what I want.