Fiancé’s family drama

So little back story:

My fiancé’s older brother is a mess. His wife cheated on him with their cousin, kicked him out of their apartment and got a restraining order on him for stalking. He isn’t aloud to see his daughters either. He then decided to start dating his cousins ex girlfriend who recently had her children taken away because she aloud another ex bf to sexually assault her kids.

Both the brother and gf were staying at a friends place. He would hit up my fiancé a bunch to come pick him up or come hang out with him and my fiancé would blow him off a lot because he really doesn’t like him. His brother stole from him in the past and he’s just a lot of trouble. One night he hit my fiancé up asking what he was doing and he simply said he was playing fortnite and asked if he wanted to play. Trying to be nice. The gf then messaged my fiancé telling him to stop bothering her bf and that her time with him is more important.... fast forward she then randomly messaged my fiancé again telling him to no longer contact her bf because he’s scum and will just make him cheat on her. My fiancé laughed and was like uhm I’m more faithful than him so idt it’s me making him do anything. It got to the point where she was harassing him accusing him of hanging out with his brother and hooking him up with random chicks. But my fiancé never hung out with him. The harassing got so bad that the people they were staying with kicked them out. Now they blame my fiancé for all the issues in their lives and have been making fake profiles harassing us daily. Saying they are gonna come to my house and stab my fiancé. That they are gonna call the cops and have my fiancé arrested. They’ve threatened to call cps on me and say I abuse my kids. I was told that I better hope I never run into them cause they will kill my unborn twins. Then tonight they blew up my phone saying my fiancé cheats on me which I know he doesn’t and this was super comical to me. But again they started threatening my kids and my home. Idk where they are living to file a police report and the messages are on fake profiles but people we know confirmed it’s them. Plus the crap they say make it obvious. But I just wanna get rid of them for good they are super annoying. Im honestly just worried they are gonna send people to my home and something is gonna happen. Sorry this is so long just needed to vent