when I definitely did have time, I just forgot.

Start with stop lying. Forgot? Just say that. It happens. Not a big deal. But if it IS for some reason(medicine or something very limited), then you can write it down or something.

Explaining your motives and actions isn’t toxicity.

Overdefensive stanse? It means you understand that you fucked up but search for excuses. That’s stupidity. Fight with that. But defending yourself against illogical pretensions is totally ok.