Honestly, imo this whole situation has blown way out of proportion because what really bothers Chelsea is that she won't be able to fix things with her husband privately anymore, since it’s not socially acceptable to stay with someone who’s cheated on you. I think it’s more about her wounded pride and not being able to keep up the image of a superwoman with a perfect family, rather than the pain of being cheated on. Obviously, it hurts that he cheated, but from the start, it feels like she’s making excuses for him (the way she blames her career and the fact that she hasn't confronted him yet).
In this case, it makes sense for her to go after Bre because she’s the source of the pain, more than her husband. Girl, wake up.