I'm Sleeping with my Supervisor. HELP!

Hi All, I am new to the Boards and in desperate need of advice. I would typically consult my friends, but this needs to be kept on the DL.

In May, I completed my Master's Degree in a Program that required me to meet with a Doctoral Supervisor for one hour each week throughout my second year. While there is nothing in a "Code of Ethics" that prohibits a platonic / romantic / sexual relationship with a Supervisor, it is strongly recommended against. However, our Program is small, and the Master's and Doctoral students share similar social circles.

When my Supervisor and I met in Sept. 2013, I thought she was cute, but rarely thought about it. She knew I was an open lesbian and I knew that she had a boyfriend of five years, but for the most part, she was strictly business, not even wanting to know if I had a dog, sibling, or what I did for Thanksgiving. What's more, we seemed to have fundamentally different beliefs about our field, and often got into heated, probably unprofessional arguments. There were a couple of sessions in which she got teary-eyed, and I became so angry that I'd start to shake. Everything came to a head in March 2014, when she attempted to have me REMOVED from the Program, stating that I was making minimal progress. However, after several meetings with my Adviser, the Department Head, and Internship Supervisor, it was decided I could finish the Program and graduate. Our final session in May was awkward and tense, it was like we couldn't wait to get out, but at the same time, couldn't get out of our chairs. We left saying we cared for one another, tried hard with one another, but we weren't a professional fit.

Fast forward four months. Although I graduated, I still have many friends in the Program and thus attended a "back to school party" three weeks ago. Long story short, my now ex Supervisor was there, and in what is now a blur, we ended up at her apartment, sleeping together. I'm not going lie, it was probably the best I ever had - a weird mix of angry, passionate, and tense. But at the same time, I think we were both left in utter horror and shock. We met two days later, and the conversation pretty much went like this - her saying it was the most horrible, regrettable thing she's ever done, and me telling her I became physically ill the next morning from sleeping with a pretentious snob. I know, I'm so mature, right? But here's the kicker, since then, we've, well, drunkenly hooked up four more times, and most recently, the phrases "I can't stop thinking about you," and "I love you" may have been mutually exchanged. Since that night, we've texted here and there about our days, and even met up for dinner in which I had simultaneous feelings of being incredibly whipped by her, yet thinking "what a snob."

SO, that's my story, and I'm left sitting here thinking - what the ---- am I doing? I love her? What? She has a boyfriend of five years? What? We've agreed to talk tomorrow night when she returns from a conference, but I have no idea where to begin.

Anyone have advice / thoughts, been in a similar situation?