a good simplified summary from huffpo (edited):

Making the entire scandal seem messy and complicated is exactly what Trump and his allies are aiming to do in advance of this week’s first House hearings in the impeachment investigation.

Here are the key facts:

- Trump pressured a foreign country to investigate his political rival.
(Both Trump’s assertion about Biden and his claim that Ukraine interfered in the 2016 U.S. election are conspiracy theories.)

- Trump withheld U.S. military aid to Ukraine.

- The White House tried to cover up Trump’s actions.

- It’s not clear what, if any, role Trump had in this cover-up.

- Rudy Giuliani had an outsized role in foreign policy, despite not being in government.

- The whistleblower complaint remains correct ― and largely irrelevant.