The battle of the bedroom (Season Five, Episode Four: "Fifty-One")
When humiliating yourself in front of your sister and brother-in-law by faking a suicide attempt in your backyard swimming pool becomes preferable to listening to your monstrous husband talk about how good the two of you are together for one second longer, it's safe to say your relationship is on the rocks. Enter Walter White, World's Worst Marriage Counselor, physically and verbally menacing a desperate Skyler into acknowledging that she has no choice but to stay with him, and let the kids stay as well. Her hateful last line of defense – she can wait until his cancer comes back and kills him – is the first time Walter's taken the kind of emotional abuse he's been dishing out for months. A few days later Walt will tell Jesse his meth business is all he has left; this is where he found that out for sure.