As his hand rests on her shoulder, she lets her eyes close for a moment. This existence doesn't allow for many moments of weakness, but she can let herself have one now, just for a little while at least. She raises a hand of her own, places it over his and squeezes gently. It could be worse after all, she could be alone in this.
"You're strong, you'll get through this. It will get easier," she's much more firm in her convictions when assuring Castiel than herself, and this at least she can get behind. He's handled this transition much better than she had once expected of him.
"It is a better life, I promise you. Freedom is something that should be cherished. And I'll help in any way I can, all you need to do is ask."