fantasize about being with woman but cant do in real life, help?

ok, this is the story before the "married" life, i was a party fanatic, drank, sex with other guys, more drinking sex blah blah, then i was living in an apartment to 3 lesbians, was always interested in their culture/lifestyle however you want to call it, well one nite we all hung out and one of them had a thing for me, we played truth or dare, well you know what happens next, i was dared to kiss a girl lol, anyways we kissed i had to force myself to do it, well after the "kiss" she wanted to pursue into relationship and i just cant get myself to, i felt uncomfortable, felt out of place, i just told her i wanted to be friends and fortunately we are still friends lol, fast forward to now living with my fiancee 2kids, and i havent thought about her in that way but i do get this attraction to certain types of woman, and funny enough my son's preschool teacher is one i am attracted to, i fantasize about being with her but when i do think about kissing her i just cant get myself to get pass that point. can someone tell me what i am feeling and why i am thinking about this???