Why Was I The Only One Arrested And Charged?

So for context me and my girlfriend got into an argument, it got heated I saw her body turn and knew a fist was about to fly into my face so I grabbed her and pushed her, she then asks why I would do that since she was going to “stop herself from hitting me.”

She then tells me to leave my own house which I refused, she calls the neighbor and her parents to come make me leave. The neighbors boyfriend and one of his friend come in soon after without saying anything so of course I go out there and they’re telling me to leave my own house saying they need proof that it’s my house. I tell them I don’t need to provide them anything and that they actually need to leave. They refused but eventually leave.

Her mom then comes in and is clearly drunk, smells like alcohol, acting unusual telling me to leave, I tell her that I’m not going to even have this conversation with her and she start literally snarling or growling at me calling me names ???? so I try close the door to my room to stop contact since I wasn’t going to put hands on her and force her to leave. She say “no no no” pushed my door open and starts attacking me.

This is when her dad and two men try and throw a log at me from outside the window trying to hit me with I but couldn’t get past the second pane, they then break the door down and enter with knives, chairs, the log and a cooking pan as weapons. The mom runs out claiming I “hit her first” and my then girlfriend is screaming and yelling telling them how she hit me first and telling them to leave actually. That’s when her dad starts flipping out on her blaming her for the whole situation and telling her to “gtfo.” She eventually listens and her mom calls the cops I believe.

Since they outnumbered me, were all significantly bigger than me, and had weapons, I pull my knife out to defend myself, they stay by the front door threatening me, saying things like how they’d “smash” on me, telling me to put my knife down (as if they aren’t breaking, entering and threatening me in my own home with weapons). I obviously refused right I’m not about to just get killed and let it happen. They eventually leave when the cops start coming after about 5 minutes and when one of them starts gaining some sense saying how he shouldn’t even be doing this since he just had a baby.

The cops get there called by I believe her mom for the situation where she attacked me, they ask my ex if I hit her and according to what she told me when I was in custody, she told them that I didn’t hit her and that she didn’t want any charges brought on me. The cops then take ONLY me to jail under the charge of domestic violence. Not the ones who broke into my home threatening to kill me, not her mom who refused to leave when I told her to then attacked me when I refused to converse with her any longer, no one except me.

Why can something so perverse happen against the actual “victim” of the crime?