Why would I risk ruining my marriage for sexual attraction?

I am married and love my husband very much. 8 months ago at a work event I had a few drinks and kissed a colleague who I was physically attracted to. Since then we have continued to fool around on a regular basis (though we haven't slept together). We work closely together and the sexual attraction is very strong, to the point where we have fooled around in the office. Because we are colleagues it's very easy for me to go for drinks after work or stay late without making up elaborate lies or inconveniences to be with him. I don't have nearly the same feelings or respect for him as I do for my husband, it's just fun and exiting. But emotionally I am a wreck with guilt and confusion. My husband means everything to me and I don't know what I would do if I ever lost him. My question is, why am I risking my marriage for sexual attraction to someone who doesn't even mean that much to me, and how can I stop?

You are playing with fire. Find a new job and stop using alcohol if you want to save your marriage.