I think the affair doesn't come out UNTIL Sean returns from his suspension, it may actually end before that. My bet is that the affair ends before it comes out.
They have paced this storyline terribly, starting things off too quickly at Christmas and then going round and round in circles for much of January. They should have spent several weeks building things up.
They can't have the Stax going on and have the upcoming Jean storyline, one will have to make way for the other.
The interesting thing is the foreshadowing about Brian Slater. That scene between Jean and Sean was designed to throw us off.
Remember Jean complaining about Stacey coming between her and Brian? I don't think the father did anything to Stacey, but he may have abused Sean and was "grooming" Stacey.
The father was obsessed by rules, and he broke them more than anyone else.