Captain Antilles has no relation to Wedge. The Captain was the man choked by Darth Vader on the Tantive IV.
I beleive the crusade is the Clone Wars, where a major battle takes place on Tatoonine. Obi and Ani are there, and something happens to his mom in the process that the Emperor turns against the Jedi to convert Ani.
Another possibility is a love triangle between Obi, Ani, and Ami (this sure does get confusing with names
). Hence why ANi fights Obi over the lava pit.
My personal theory is that Ani said he would do anything to free his mom. This means he went to seek more power. The only way to do that is too go to the Dark Side.
"Have no fear, your local Grand Admiral is here!"