Being Harassed Online By Stepbrother + His Fiance

Location: south Carolina

We have never got along. I only kept in my friends because we're related. We never interacted at all until a few days ago.

His fiance randomly commented on my (3 year old) picture showing she had been digging through my profile. She posted "hope you get caught chomo"

I have no idea wtf she was even talking about, and messaged her. After this i get tons of notifications. She commented on almost ALL my pics that i was a chomo. I messaged her and she told me I can discuss it with my stepbrother/ran off and blocked me

I messaged my stepbrother asking what she meant and he accused me of telling people he was a pedophile

After a long argument he admitted in the chat himself that i haven't touched a child and hes giving me a dose of my own medicine

I made sure to screenshot and emphasize that as proof that I posted on my public profile after his fiance bombarded my pictures

This came from his fiancé herself, she told him that in high school (we went to the same school) i told everyone he looked at porn of kids

This wasn't just gossip, when we were alone as boys he "curiously" googled you know what to see what it looked like. This only happened once and I did tell friends about it.

I didn't mention it ever again.

Now he is sending me threats that he's going to post my face on sex offender pages, tell people I talked to minors, and wouldn't stop even if I blocked him

I have all the screenshots but family (who are too lazy to actually read the screenshots and my constant disclaimers) are only seeing the chomo comments and making their conclusion there.

I even have a distant aunt share one of the pics to warn everyone

So now its attracting harassment from other family members

How do I go about this? I cannot keep posting/correcting his lies and the lies are spreading much faster than I can keep up with. I'm not going to have the reputation of being that type of person. That would be a nightmare for anyone, so it is something I take seriously.