Need advice...

Narc and I used to work together in the same school abroad. Now, he's gone (thank God).
School has just started and there is a bunch of new teachers who just arrived. One of them is a good friend of mine and ironically, she's taking my ExN's job.
This is year I didn't get the job I wanted. My boss told me it was because towards the end of the year I had stopped being professional (which is true, i was a mess) and that some people had a bad influence on me (I knew exactly who he was talking about, my ex). It made me feel sick to the stomach that there was yet again another unhappy consequence to that crazy relationship. For the first few days, I was in panic mode, back where it all started and feeling professionally inadequate. It was a difficult start. But, it's not over.

My ExN has a couple of guy friends at school.

Since school started a week ago. A senior management guy mentioned to my friend about ExN and I and said we were on and off. I didn't like it but he said nothing compromising.

2 days ago, another friend of his, who now shares an office with another good friend at school this year, asked about me and him and wanted to know what was going on. She said I'd moved on and that they wouldn't cross stories.

That day, the same guy took the newbies on a city tour, my friend went along. IN FRONT OF EVERYONE, he brought it up AGAIN and to my friend and said she didn't have the full story, that he had his version etc... that he was his good friend, etc...My friend cut it short and said it wasn't the time nor the place to discuss this and that she already knew what she needed to know anyway.

2 days ago, I get hoovered after 2 months of NC. I came with the best intentions of making this year a good one but everything and everyone is reminding me of that asshole of a man. And now, they make it sound like I'm a bit crazy too. There are a few people at work who know too much and they act weird around me. I think my ExN told them about my snooping and email checking and made it sound like I was an obsessed psychopath. Part of me wants to know "his version", because there are still so many things about me I don;t understand but it's too dangerous. I won't go down that road and reopen the can of worms.

His guy "friend" is also a guy who on a night out tried to kiss me. I told my ExN about it, and he confronted him about it, or so he said, even when I told him not to. I was just fed up because his friends didn't seem to know we were together, the same night someone had asked if we were "fuck buddies". I was upset and I told him, maybe I shouldn't have.
Today, they are great friends still, they probably had a different type of conversation something along the lines of "she's trying to make me jealous, she's like this, she's like that, you're great and she's fucked up, let's be friends". I feel like a freak and deranged sometimes. I'm going slightly crazy with all this. It's too much to bear sometimes.

Monday, I want to go talk to that guy to tell him he has to mind his own business but in a non-confrontational way and without looking crazy.

What and how would you say it?