So am I wrong? **LONG POST**

I need to know if I am in the wrong here. I'm conflicted but I don't think I am. So my family is in turmoil practically, I talk to my mom, dad, and brother. That's it. So I have a sister. She's got two kids, and a pos old man. So her boyfriend threatened to kill my kids a year ago. I've literally only seen her oncesimce that without him. So I just moved into my recently bought home. And my dad came over yesterday I have 4 kids (I'm currently pregnant with my 4th). So my two oldest went with their grandparents thinking nothing of it I trust them. So my sister and I don't get a long she's not the best person to be around and the boyfriend thing was the nail in the coffin for me truthfully. So the problem is that I call to check on my kids today they invited her down there, which is fine it is their kid but I have said that I do not want her around my children at all. So I find this out I'm clearly upset but my husband got me to calm down and try to play nice so I was going too. I told my mom when I got down there I did not like the disrespect that I got because they are my kids and I didnt want her around I would have picked them up before she got down there. So I didnt say a word to her and my mom tells out as she walks in that I dont want her around my kids. So with my kids and hers in the room my oldest is 6 by the way, she calls me a bitch and all I said is that your boyfriend threatened to kill my children that's not ok then goes on to defend him and says that he did say that. So she is going off also making up lies which she normally does. but you defend a man who threatened to kill my children over you leaving him for hitting you. What do I know though. I wasn't rude I didnt really get to say anything at all truthfully. So she left. I did get rude with my mom stating I needed to know who was around my kids and it is rude as hell to bring someone around my kids I said I didnt want around, also not saying they can't have their other grandkids or daughter there just the fact that it was disrespectful to bring her blatantly around my children. So i remained calm though, never raise my voice. Until my mother told me i was the bad guy, my sister had already left at this time. I did yell at this point because I was backed into a corner, I trusted you with my children and you chose to do one of the only things that would really upset me. And she acted as if she was the victim out of this situation. she caused it, I didnt yell out I dont want you around my kids and I dkdnt know she was there until,she was there already. My mother put this situation on purpose. at the end of the day I will not ever be ok with someone who had threatened go kill my children and it's being forced upon me. I only feel bad for yelling at my mom, but she did need to hear where i was coming from If I want to deal with her il do it on my own time not when you do. I dont think I'm wrong ists already a long post so I can't get into what she's done before all of this, which is a lot truthfully. Just I kind of needed to rant and ask for advice truthfully because I dont trust the situation at all. I feel betrayed honestly... and then to be made out to be the bad guy does make me mad because I wanted to avoid confrontation. Also I'm 30 weeks pregnant that's high risk who doesn't need stress...