I think you already know the answer to that

"Don't tell her about anything, and just say you didn't find out. Or… if you can, just tell her I don't remember a single thing, Klaus. It'll be easier that way, easier not just for her… but for me as well."

Yulis pressed his lips and studied Klaus's stunned reaction. He nodded slightly, turning on his heel to leave. 

"Hey!" Yulis stopped when Klaus suddenly appeared in front of him, blocking his path and grabbing his chest aggressively. "What did you say? You… remember everything?"

Yulis raised his chin and kept silent for a moment. 

"Yulis…" Klaus tightened his grip on Yulis's chest. "If you know Silvia remembered, why aren't you saying anything?"

"Because… I don't see the need why I have to tell her?"

"You —"

"Klaus, it's better not to dwell on what happened before the regression." Yulis cut Klaus off offhandedly. "You do what you need to do, and let me do mine."

"And what is that you need to do, Yulis?"