I'm kind of confused on why both churches went so far as to excommunicate each other.
You may want to include a reference in the title to some kind of Christianity
hi! you'll find several lengthy responses to this question in these posts
What events lead to the East-West Schism and why couldn't Rome and Constantinople reconcile?
Could you explain why the eastern schism occured and what it lead to?
At the time of the Great Schism, what were the main differences (doctrinal, aesthetic, architectural, stylistic) the Latin Catholic and Byzantine Orthodox Church ?
Why did the Great Schism happen, and why did the Eastern and Western churches develop different traditions?