I am torn up about this and unsure of what to do to move past how I feel.

I am a happily married man with two young kids under the age of 2. Earlier this year I started getting close to a female colleague of mine at work. I always thought she was nice and a good friend, but never much more than that. By pure chance earlier this year, we ended up going out on our lunch break alone, rather than with other colleagues. I used to always go in a group, but there were a couple of people she disliked in that group so she usually went to lunch alone.

We found out we had a lot to talk about and we started going out alone together more regularly until it has almost become a daily occurrence five days a week. She has a busy social life and chats a lot with other friends, but I have become one of her most regular chat buddies on Facebook, mostly during work hours.

I had a hunch she might be a lesbian because she was very pro-gay rights and most of her friends in photos looked quite boyish, even though she herself looks quite feminine. Plus I thought it was unusual for someone as attractive and social as her to not have a boyfriend.

She confirmed to me that she is indeed a lesbian. Well, technically bi-sexual as she is attracted to men as well but has chosen to live as a lesbian. All her physical relationships have been with other women, and as it turns out she's quite popular with the ladies.

I have been completely honest with my wife that she is the closest colleague I have at work and that we eat together almost every day. My wife has also seen her a few times outside of work and liked her personality too. I guess it's because she knows this colleague is a lesbian that she is not concerned about the closeness of our relationship.

Lately, however, I have grown attracted to this colleague and can't stop thinking about her. She has a complex love life -- she is obsessively in love with her ex but for a while was in a physical relationship with another girl -- whom she tried to deny was her 'girlfriend' because of her feelings for her ex, who clearly is no longer interested in her and is actually leaving the country, but this has not stopped her from fantasizing about them getting back together some day.

She lives by the philosophy that are more layers to relationships than just one lover and the rest being friends, To her, she is in love with her ex but the other girl she was with is 'more than a friend', though she is not in love with her to the same extent as her ex.

I have no idea how she feels about me. Clearly we are very good friends, one of a few people and the only male friend she hides nothing from, as we often talk about sex and relationships openly, including problems in our own. She has no problem ignoring people she dislikes, so the fact we remain close suggests she at least likes me as a very good friend, maybe even something more. She says she places little value on physical attraction, but she did say she thinks my son is the cutest kid in the world largely because he has my eyes and eyebrows.

I feel terrible about how I feel towards her, not only because I know it is wrong, but also because I know there is no chance of anything happening between us. I still love my wife dearly and would never do anything to hurt her or jeopardise our relationship. But despite the immense guilt I just can't stop thinking about my colleague and secretly hoping that she has feelings for me as well, even though I know it's completely stupid because nothing can come of it even if she does. It's driving me crazy and I don't know how I can go back to just loving my wife and no one else. I've tried not chatting with her at work a few times, but as soon as she sends me a message I can't help but reply and it turns into a lengthy chat. It seems the harder I try to avoid it the more I can't stop thinking about it. Just letting things stay the way they are is torture too.

I'm so confused and feel like I need some advice desperately. Please help.