Why is my ex trying to provoke an argument with me?

So without knowing your situation. I'm guessing your ex had to provoke an argument with you because something on their end did not fall into place as planned, so as a way out. They had to point a finger at you

My daughter from a previous relationship would come over, my ex would leave that weekend n party the whole weekend away. Coming back Sunday. Leaving me with the three kids.

Our breakup process started when she started going out drinking, about when our daughter was 2

One day, I happened to walk past where my crush was with friends. Then all of a sudden they start laughing, and someone maybe him, goes "freaking (my name) with her freaking hair!" Can anyone offer insights into this? We're in middle school.

She claimed her friend who was newly single needed her support.

Fast forward to 2.5 years later. The explosive anger and aggression came back out of no where. Long texts, picking fights, threats, anger, rage, chaos.

My ex did this,

Could humans be selectively bred, like dogs, to create 2 subspecies that can no longer have offspring? Do I not understand selective breeding properly? Im not worried about the moral implications, just the science please.

Eventually the phone calls n texts slowed to a stop. Eventually she stopped coming home. And when she did it was instant anger and yelling.

Inevitably she had an explosive outrage and demanded I moved out n that it was over.

It eventually became an every weekend thing, then her friend started coming over, every single day. She wouldn't leave. And my ex was letting her invade our life.

Why am I so triggered and depressed over a minor thing?

I'm assuming she was trying to flee from accountability in her life, probably got caught doing something from the new boyfriend she suddenly had, so to get out of the spot light, she had to put me in it.