I'm a little scared to go prancing around this section, so hoping those that have finished will have a few more idea's.

Please try to avoid any spoilers that happen after act 2 first cutscene.

My major question comes from the

Fell Willingly cutscene
Wrath Trailer

In the first, Tyrael goes to stand trial for destroying the world stone, imperius seems to lose his !@#$ (which falls in line with the wrath trailer).
In the second, it seems to be happening some time during or after the sin wars? Or some time during/before the prime evils we're even banished?

What exactly, was "the trap" mentioned in Wrath? If their unity was broken back then, why is it Tyrael, that breaks the unity?