Where exactly am I going wrong here?

I need to sign up for parenting classes asap.

Yesterday, I walked in the living room to find Austin holding his arm and crying. I asked Aidan if he hit him.

Aidan: No
Me: Are you telling the truth? (We've been having quite a large fibbing problem lately.)
Aidan: YEEEESSSSS
Me: Austin, did Aidan hit you?
Austin: Yes
Aidan: I did not!
Me: Aidan, go to the white chair (our time-out chair).
Aidan (while crying and telling me how unfair I was): Mommy, I did NOT hit him. I PUNCHED him!
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Today, Aidan was laying on the rug in the living room, and Austin was standing over him. Austin has just been trying to get in trouble lately (as if he needs to look for extra excuses!). Austin hit Aidan, and I told him to go to the white chair. When his time was up, he came back, and I said, "Do NOT hit your brother!" Austin looked at me, smiled, and then kicked Aidan in the leg. Ahhhhhhhhhh!
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In addition to this, Aidan has told both Jared and me this week that we are poo-poo's and that he doesn't love us anymore. He went on to clarify that he only likes us (which was pretty cute!).