My building administrator left me a "noise complaint" note. It was more than just that.

Soooo I'm a student away from my hometown and I live in an apartment that, fortunately, my family owns. I've lived here for four years and while I'm not the quietest guy in the world I do my best to not be a horrible neighbor; I've only received two rather civil complaints from other tenants over the duration of my stay here, which I've tried my best to heed, and I've had no problems whatsoever in the last year or so.So today I got a note from the administrator that my behavior is "very disturbing" and I need to "cease all activity after 23:00 (including talking, going out, having visitors etc)" and that "I have to always remember that I can be heard and nobody else wants to tolerate hearing whatever I'm doing".He also wrote that "after midnight it's lights out for me" using a hideously patronizing expression in my language, and that I need to "get a day life in order to fall asleep at night". The whole tone of the note was distinctly condescending, directly telling me what I can and can't do in my own house, and kept mentioning "whatever it is you're doing or want to do" as the source of annoyance.Now, I've been bringing guys over since my first year here, hell, my ex almost lived with me here for the two years we were together but I never got such a note even though I was much noisier in general, because I was careful enough to not get loud during sex.Now, after 4 years of living here and one year together with my boyfriend, all of a sudden I'm the worst, most obnoxious tenant and nobody's telling me in my face because "they just hope I'll stop" according to the note. Nothing changed in my lifestyle- if anything I've gotten quieter. Plus the building in general is full of loud tenants, you can hear kids, TVs, vacuum cleaners, the lady next door screaming at her old mother, but suddenly I'm everyone's major problem after 4 years.What made a difference? Well, I had some rather loud sex with my boyfriend at one time this month because sex is actually good for the first time in my history of dating... and I suspect we got heard.As I mentioned above, the house is not rented so I can't get kicked out by any idiot landlord, however I do feel extremely self-conscious inside my own home, and my bf texted me that he'll have a difficult time relaxing here again knowing he's part of this mess.Another issue is that I have no idea who's heard us, and getting outed to my dad by the administrator or a nosy neighbor would be an utter disaster for my life. My mom knows about me but she's not okay with it, and she won't be too happy if she learns that the whole building's heard her gay son have a good time. She's still the first one I'd call for assistance though.So what do I do, guys? This is the first time in my life I'm faced with a potential homophobic situation I can't really control, that I'm stuck in and that can turn volatile really fast. I could be wrong about this, but I have every reason to believe this wasn't just a good-hearted note about being tremendously loud in general, which wouldn't be true anyway. I'm kinda freaking out, and I'm afraid I won't be able to chill out inside my own home anymore, not to mention what'll happen if my dad or relatives find out about me in this way.Advice? :/