My partner and I had decided to keep our relationship a secret on social media, but one of my relatives saw him commenting with his ex-girlfriend and spread it in the family. My mom even said, ‘What kind of guy is this!’ How should I draw the line to keep control over my own relationships? Relatives are too nosy.
I went through the same thing, my cousin was constantly browsing my girlfriend’s profile and bringing ridiculous things to my mom. I just said directly, “Don’t look, don’t interfere.” There was a bit of hurt feelings, but I felt relieved. Solve it early, otherwise, it will cause you trouble later.
I think you need to make your stance clear to your family. Tell your mom outright, ‘We have sorted this out between us, my boyfriend’s past is not my concern.’ Say the same thing to your relative. If you express your position directly, it will ease the tension 
But why did she comment with her ex now? I mean, there’s a mistake on your relative’s part, but your partner doing things so openly is also a problem. Still, I think there are other things we need to learn here 
Ensuring family privacy comes from both communication and setting boundaries. Use a polite yet firm tone to express your discomfort. Additionally, it has been a wise decision not to be overly open on social media, so continue that approach.
But now you’re kind of giving yourself away a bit too. If you wanted to keep it a secret, you could have prevented your partner from drawing attention with comments and stuff beforehand. I think you weren’t clear from the start 
Here’s another detail: my girlfriend didn’t even notice that comment was old. I think my relative overstepped a bit. My mom is still a little mad, but I’m trying to mediate 
It’s really frustrating when relatives get involved like this, you know? Everyone wants to have a private life, after all. It might be better if you explain the situation to your mom over time. Solving things while she’s angry seems difficult.
It’s important for the family to hear things. Your partner should have been careful with their actions. The ex-girlfriend and all that, these topics are sensitive. Relatives don’t get involved for no reason. Be careful 
It’s really not pleasant when relatives get overly involved, but be careful; maybe your partner should have provided clearer explanations about those past comments or whatever. Trust doesn’t fix itself later; it needs to be established from the start.