How Can I Tell My Boss I’m Not Interested In Sex With Him?

I am a P. A. to the Managing Director of a big company and whenever we have the Annual General Meeting, we often book rooms into the hotel of such meetings for effective co-ordination. A few weeks ago, we had last year’s AGM and a few of us got a bit drunk as the meeting went rather well.
You can imagine how shocked I was when I woke up the next morning to find my boss in my bed!

He’d been flirting with me for months even though I told him I wasn’t interested.

I don’t know if anything happened between us as he looked really smashed too and I still had some clothes on. I’m currently on leave and I’m terrified of going back to work as I have developed an itchy discharge.

How can I convince my boss I’m not interested in him s*xually? I have my own man and that's enough.