How should I handle this situation?

I used to work at a Xerox store, and there was this customer who came in often. He was nice, and we shared some small talk every time he visited. I always felt a bit giddy around him, but that was as far as it went—until I learned my boss was attempting to set him up with another female employee. I figured it was fair game to reach out, as I hadn’t before, assuming dating customers was off-limits. I sent him a Facebook friend request after digging up his name online, and he accepted right away. We started chatting regularly, but he would act like he didn’t know me whenever he came by the store. This was puzzling, yet he continued to visit almost daily, which made me think he might be nervous or something. In a moment of frustration, I jokingly mentioned to my boss and coworkers that he only came in when I was working. They got defensive and pretended not to know what I was talking about, quickly changing the subject. I realized I was being petty, but they had treated me poorly, so it felt good to retaliate a little. Eventually, I quit due to the toxic work environment, and within a week, I landed a much better job. I reached out to him to let him know he’d have to deal with my old coworkers from now on, joking about how strange they were during their interactions with clients. After that, we talked less and less since I was working longer hours, and he was busy with work and college. Recently, I noticed he had unfriended me on Facebook, although he still follows me on Instagram. When I messaged him, he was surprisingly rude. He ignored my question and basically ghosted me. I can't help but think that perhaps my boss or coworkers mentioned my earlier comments to him, which might explain why he became distant after showing interest. By the way, my former boss has been posting about me on the store’s social media, almost calling me out after I had gone above and beyond for that job, even working through my lunch breaks. She’s just upset that I quit without giving a two-week notice. Should I just let this go? I don’t have strong feelings for him—it was still early in getting to know each other—so I’m just feeling confused.