Oh, I'm pretty sure you are going to find new levels of hate for Michael as the series progresses LOL!
I totally understand how you feel about them knowing Jess was alive, and it's in the back of my mind. But the reason was simply that it would have made it super hard for the pace of the story to have that kind of grief to deal with. Basically, since jess is based on a friend I have, I know that I couldn't just cry it out and move on. It would color everything I did and felt for a long time to come, so not just the pace of the story but also the atmosphere would have to be much grimmer. That's the reason, even though I know that it would be a lot more exciting and poignant for them to think she was dead and then find out she wasn't. Trust me I do know that.