Would you be upset?

This is going to be a long one so buckle up.

A little back story: My sister is divorcing her husband who is a total POS. He's abusive in all ways not only towards my sister but to his step daughter and his own kids they have together. I've seen him lay hands on my sister, I've seen him push her around. I remember being 14 and standing in between him and her just to stop him from hitting her. I've heard him call my neice (step daughter) a whore, that she will be just like her mother who got pregnant with her at 15, worthless, and so much more. My neice even moved out of my sisters house to live with my mom because of how bad it got. He puts his own kids down daily, his own kids now don't even want to be around him. Since my sister has filed for divorce he's been to jail about 6 times, for previous charges, drinking and driving, harassment, trespassing and DV. He's threatened to kill himself over and over while drunk. Even caused a scene in the bar where they had to call the cops on him. He broke into my sisters house one night and choked her 3 times. One of the times was to the point where she almost passed out. She had to text her daughter to call the cops for her. That's where he got the DV charge.

So now to present day, 2 weekends ago my mom babysat our two year old over night for us. Well we recently found out that my sister and this POS were together even though there is a restraining order. I was told it was because she needed help with a couch. During this time my mom and her husband (my step dad) kicked my neice out of their house because they were tired of her taking advantage of them. And since my sister was supposedly not with this man anymore she needed to go back and live with her mom anyways.

Come to find out this guy and my sister went back to my moms house while my mom already had our child in her care. And the excuse is because he had a truck and had to help my neice move her bed. Which is total BS because there are 5 of us in the family with a truck to help. My husband and I both can't stand this guy. Even before him and my sister were getting a divorce he was already dead to us. And we kept our son away from him. My mom didn't even tell us what was going on, or that he was at her house. I had a feeling he was because stuff just started to add up in my mind and last night my other sister and husband actually confirmed that we were right.

My husband was PISSED which I agree that he has every right to be. I was also pissed about it. Not only is my mom allowing this guy in her house, and with our kid there without letting us know, but she's also just ok with the fact my sister is with him?! I guess I just don't understand it. So my husband called my mom and voiced how he was mad. My mom then said she couldn't even remember if she had our child which set him off even more. How do you not remember if our TWO year old was in your care?! So my mom sent me a couple text messages this morning which I'll post. But I just don't even know what to do. I'm literally stuck in between my husband and my family. But I do have to agree with my husband on this 100%. I mean are we wrong to be upset? I'm so sick that my family sees absolutely nothing wrong with this whole situation. So of course I'm the one who is now tearing the family apart because we said something. It's like my sister is gonna have to end up in a body bag in order for them to actually care that this guy is beating on her not only physically but mentally too.

I just need some other opinions on this I guess. I've been crying all day yesterday being stressed over this. I guess I'm the bad guy and ruining our family because I think it's wrong and voiced my opinion unlike everyone else in my family who will just talk shit behind your back but not say anything when it comes down to it.