Let’s be clear about something…if Belle hadn’t stormed in when she did I’m like 99% sure Killian would have told Emma what was going on. Emma noticed something was bothering him, confronted him and he said it was a long story. Not one for right then (where they could possibly be overheard). Remember at this point he’s only been cursed for like 24 hours. It’s a heavy burden in an apparent no win situation. This was after his first instinct being to tell the Charmings (which again got blocked).
Bottom line: Emma knows something isn’t right. She knows that something pretty big is going on with Killian. And she knows he would never put her (or anyone she loves) in danger on purpose. She knows this because she knows him. Better than anyone else.
So let’s say for argument’s sake…Zelena does take Henry and that’s how Emma finds out about the curse. First, it’s completely Zelena’s MO to fuck with people. She’s impulsive and impatient, when shit’s not going her way she finds a way to force the issue. She wants Killian to kiss Emma to take away her magic. She told him that she’d start offing people in Emma’s life if he didn’t. She specifically threatened Henry, so it makes sense she’d start there.
Regina told Robin tonight that nothing is worth the loss of a child. I don’t think that’s an accident. If Zelena is threatening Henry next week, Emma’s going to have the same reaction. She would gladly sacrifice her magic to protect Henry. So if she understands that that is the choice, she’s going to kiss Killian.
Of course, Zelena’s completely underestimating Emma’s feelings for the pirate but whatevs.
Emma’s magic is strongest when she’s emotional. It’s driven by her emotions, most specifically her love for the people in her life. Emma’s magic is white, pure as snow. (Ha, ha Eva) So if she’s trying to save her son from Zelena and her almost boyfriend from a curse…what kind of magic do you think our Savior could muster then? Maybe the TLK kind? If we’re gonna find out who cast the curse next week (assuming it wasn’t Zelena herself which is…weird), I would parallel that with it being broken. But that’s just me.
When Emma has all the facts she’s going to be pissed at ONE PERSON: Zelena, the Wicked Witch of the West. Zelena’s the reason all this is happening. Zelena’s trying to wipe Emma herself and most of the people she loves out of existence for pete’s sake. Jen herself posted set photos that have Hook right there with Emma in 3.20. We have various reports of Jen and Colin filming together in 3.21 and 3.22. While the situation isn’t ideal…it’s not a deal breaker. The choice is still ultimately Emma’s. And she’s still going to want Killian by her side fighting the good fight.