Well, an hour in the game taught me the basic stuff. I kept all my hordes as money making machines except 2, that were more than enough to deal with the Ostrogoths. The mission you talk about is, near-impossible to take your wife's side! I saw the penalty, nearly crushed me. I loaded. Still couldn't go with it and made the exact same option. I was just decimating most of my forces.
My problem is: After getting victory for the Expedition, by giving Justinian Italy... I went to attack the Visigoths and declared independence.
It really hurt financially. I mean, I have 4 armies and 4 provinces and I need to sack 1-2 provinces per turn to stay afloat, cause because I am "Terrifying" nobody wants to trade with me. My 200K income simply evaporated.
Now I have to deal with religion, and trade, and food and sanitation and governors etc...
I have some damned good armies and I don't want to disband them... it's near impossible to make them again with their nice weapons and armor.