Horrible SIL

So I’m pregnant recently my boyfriend texted me that his sister my “sisterinlaw” Who Is 19 same age as me btw Was texing my sister and apparently my little sister texted her that her mum Is a bitch and He was having a go at me saying Tell your sister not Call my mother that and that i should give her respect and such ... well i decide to talk to my little sister Who Is 13 i asked her to give me her Facebook so she did I scrolled all the way up to see who has messaged whom first and ofcourse my SIL was starting the whole thing so I called my boyfriend back to tell his his sister started I even sent his screenshots and it was clear who started it and he told his mum that it was my SIL that started then they all were having a go at him saying he is standing up for me and they don’t want him in the house that he should go to me he told them that’s he not standing up for anyone and he told them to stop however but he doesn’t wanna argue with his mum ... anyway i read everything What my SIL was texing my sister she she was having a go at my little sister Calling her names litreally bullying saying súch as Why did you send me a friend request i dislike you little slut and my sister replied I never sent you anything then again My SIL texted her Very ugly words and my sister was just sending her likes totálny ignoring her and then she said that she will come and beat her up and my sister texted her back saying i dont have time fór you you idiot then my SIL replied you mother a idiot the biggest slut , then my sister replied saying she could be an idiot but she’s not a bitch like yours then my SIL she started spamming her with messages bringing my whole family down and cursing them anyway it was clear that his sister started so I messaged her hey what’s going on why are you arguing and she immediately got aggressive with me told me to hit the fuck up telling me to mind my business and that sill will beat my sister up and she started calling me names aswell and cursing me bare in mind she started all this and how could his family treat me like that I’m pregnant with his baby and there littreally cruising me out also she said she doesn’t care I’m pregnant she will beat me aswell I just find it funny I don’t know what to do anymore they really dislike me even though I never in my life done anything to them .