Bianca isn't acting all goody goody, she knows she did the wrong thing with Heath. Heath didn't tell her how he felt about her either, so how was she to know that he had more emotional feelings towards her. The only thing that she has done wrong is sleeping with Heath when she didn't have those types of feelings for him, she was only acting on physical attraction, not love. Once she realised her true feelings she broke it off with Heath. She was never with Liam either times that she slept with Heath (the first time was when Liam was in rehab and they had broken up and the 2nd time at the cottage they weren't together then... there might have been a third time but unsure).
Bianca is still my fave character and I'm so glad she's back with Liam and also happy that she yelled at Charlie as well. Hopefully though those two will be friends again cos I like their friendship.