I'm dating a married man !!

So, I am dating a married man. I met him at work in October when we both started. He is my manager and a respectable man in the company. He, unfortunately, has a wife and 2 kids! His last child was born a week before Thanksgiving. (At that time we weren't speaking on an intimate level). Right after Thanksgiving, we started flirting a lot at work. Passing notes, locking eyes, smiling...the whole 9 yards. We both knew we were playing with fire. One day he asked me to go out for a drink after work. I agreed and from there it was all rainbows and butterflies. We chatted for hours after work at the bar. At the end of the night, we made out pretty passionately. When we locked lips, he made me feel like no other man had. It was almost like love at first kiss! From that night on we constantly texted, talked, and flirted more and more. It got to the point where we were seeing each other after work, before work, and even on his days off. We had this chemistry that made us both feel so alive. I've never had anything like it. Our romance felt like something out of a movie. He wrote me songs, poems, sends me flowers, takes me out on dates...etc. On 12/12/12 we made ourselves official. We were/are in fact a couple. One day he sat me down and told me that he had fallen completely in love with me and wants to be with me. That he had no idea what love was until I came along. He told me he is planning on leaving his wife in a couple months and living on his own. He said that he was planning on leaving for a while before I entered the picture. He also told me that his 2nd child wasn't planned, and that's what he's staying now for. His wife knows he doesn't love her anymore and is heartbroken. She's also found songs he's written to me and texts between us. He even got his mother involved and his mother is telling him to leave his wife! I feel like a horrible person, but at the same time I am so happy with him. He told me to wait until he sorts everything out in a couple months, but I'm not sure if I should. What should I do? HELP !!!