my mom keeps going back to her abusive boyfriend

my mom keeps going back to her abusive boyfriend

i’m currently 20, my mom (39) has been with her boyfriend (38?) for about 13 years on and off. he’s always been physically and mentally abusive to my mom and i’d say he mentally abused the children in the house. the past 5 years have been the worst. i moved out about 4 years ago this was because he threatened to kick me out, beat me up etc. he had occasionally been this directly aggressive toward me but never really threatened me with violence. this scared me because i had seen what he did to my mom and i know how he worked. 2 weeks later he threw my mom across two rooms in front of my , at the time 3, 5, 9 and 15 year old brother. he then proceeded to hold my FIFTEEN YEAR OLD brother up against the wall by his neck for trying to defend our mom - bear in mind my moms boyfriend is bigger bodied and relatively tall and my brothers a twig i no longer felt even remotely safe knowing he now had escalated to physically attacking the children in the house so i left. and he stayed for 3 more years. my mom chose him. about a year / a year and a half ago they split, he moved out, my mom put their home in her name, we thought he was gone. she was hiding that she was seeing him and hearing me scream cry when i found out they were back together didn’t change a thing. i went no contact for about 6/7 months, we eventually got back in touch because i made an attempt on my life. she was still with him but i just needed my mommy so we were back in contact. fast forward to the christmas that has just gone he was arrested for assault and drunk driving i think. my two little brothers woke up on christmas day to no dad but a few more holes dotted about the walls. my mom was doing everything right, she was following through with the case against him , she went no contact i was so proud. HOWEVER my brother went through her phone and found messages of them talking again planning to meet saying they miss eachother. two particular parts of the messages make me sick to my stomach - she got annoyed that he said he was the only one making an effort, and she said she drives specific routes on the odd chance she’ll see him. now i fully understand how the cycle of abuse works i’ve been privy to it before i left primary school so i can so whole heartedly sympathise with my mom but im at a point now where i can’t do it anymore. she didn’t protect me and she’s putting my brothers into dangerous situations for what? i think when me and my brother decide to tell her we know im going to have to go no contact but then what about my brothers? of the ones in the house still they’re all 13 and younger i can’t just leave them to go through what i did. i’m just really stuck on what i can do i feel so powerless.