I dont understand?

okay, I just want to let it out o my system, and try and feel better, sorry if this annoys people… alright so about 2 years ago on a Wednesday night, my mom tucked my, my little sister in, and my brother in for bed.She read us bedtime stories and on… The next morning we wake up and my dads crying and waiting at the door… it turns out she had let about an hour after she tucked us in.. she old my dad that she hates him, she hates us, and she has no freedom in life, she wanted out. Anyways so later on we found out she was cheating on my dad for about four years, and they had been married for 24… few months down he road they’d gone to court, and we had to go for weekend visits.. I hate her! the first day we went to her place, her asswhole boyfriend introduced himself and said: “ this is my house my rules, dont like em, get the hell out! you three will sleep in he basement, dont come upstairs unless I say… my mom agree’d with him.. stupid as we were, we didnt tell my dad right away. Anyways as the visits went on she started abusing us. There were brutal incidents were when my lite sister was 8 my mom had choked her well because my mom sicotic! Another one was I told her I hated her and her boyfriend and I didnt want to be there,she had then pushed a table against me, full fource so I couldnt breathe.. she had also chased my brother around yelling at him while he had a broken knee cap.. anywho…we finally got enough evidence so c.a.s could take action and polcecould harge her.. she never went to jail for some odd reason, but no these days we dont have o visit her, and all, but the only question ha brings me to tears is why?? why would she do this, say those things?? if she didnt like her life, why bring us into this world and torture us? I;ve asked her this but she tells me to f#ck off all the time? im 13 and this has scared me for life… sorry to sound stupid , I just want to know