I’d even throw my own mother under the bus, and trust me, I have

Hi, I do not understand why the kid (the narrator) says "trust me, I have". Where this "have" comes from? I'd say: I would even throw my own mother under the bus, and trust me, I would." Isn't it right?
"But if there’s one thing you should know about me, it’s that I have NEVER taken blame for a fart. I’d even throw my own mother under the bus, and trust me, I have." (Diary of a Wimpy Kid, Double Down, Jeff Kinney)

I have (thrown her under the bus). He's stating that he would (future) and he has (past).

SoothingDave said:

I have (thrown her under the bus). He's stating that he would (future) and he has (past).

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But he hasn't actually!

He has- throwing someone under a bus is not literal. If you throw someone under a bus, you fail to support them or abandon them.

It's a person being scapegoated, or meant to take on the blame. The person being thrown under the bus takes the blame, perhaps unfairly, for something. A sacrifice is required.

Often used in political contexts. Something bad or embarrassing happens. Some staffer is blamed and fired.

I assume he means that he has farted and blamed it on his mother.