I got really emotional (bipolar episode) and sent hate-mail to my past liberal teacher who used to bully me. Then someone who claimed to be a police officer texted me saying that they have a...

Sounds like bullshit. You would get a summons in the mail first, or they would come see you in person.

They don't typically call or text you to warn you they are coming to pick you up that would be stupid for obvious reasons.

Also I don't know where you live but afaik you don't get an arrest warrant for a harassment complaint.

Police don't notify people about outstanding arrest warrants. They execute the warrant to effect the arrest.

There are some exceptions but unless your related to a police officer or a high politician your not going to get a courtesy notification to arrange a surrender.

Definity not real and what they did is a crime.

Almost certainly bull. You can contact your police department to see if they have a warrant out on you possibly. If they don't you could file a police report and give them the record of the text/phone number and they may decide to go after whoever it was for impersonating a police officer though.

lol you could report that number to the police for pretending to be a law enforcement officer

Probably nothing. Still, sending hatemail to people is a bad idea. Although its legal in freeze peach land, its an asshole thing to do. I‘m sorry they bullied you either way.