Just a couple of things I have noticed that might help. The crusade ends if the pope dies or it is completed, so you can find a way to help him meet his Maker or just wait it out. Also as far as getting ceasefires with the AI having a crusader army doesn't make a difference. The AI will send crusades against Egypt and declare ceasefires a turn or 2 later while the crusade marches to Jerusalem. Then when they attack the city they are at war again. So I don't think the crusade should impact your situation. Worry more about whether the AI is in a parleying mood.