Pretends she didn't know

"I'm sorry," Cynthia says, "This is just... This is a lot to take in."
"I know," Jade says, drawing Cynthia into a hug, "Did you have any suspicions?" Cynthia is transported back to the day she discovered that Mark was cheating on her. She hadn't had any suspicions whatsoever, and she felt like an idiot for it.
"None," she replies, tears welling in her eyes, "Why would he do this to me? I thought he loved me."
Even though she's pretending that she didn't know about what happened today, the tears are real. Despite the exhilaration of the **** she's been carrying out, a significant part of her is still hurt and confused, mourning for what she'd thought was a perfect marriage and cursing the fact that for some reason, she just wasn't enough for him. She buries her face in Jade's shoulder and sobs as Jade strokes her hair until she's done crying.
"I'm sorry," Cynthia sniffs, wiping away her tears, "I feel like Vanessa, needing to be hugged and comforted in the middle of a party."
"Ugh, Vanessa," says Jade, "I want to say I can't believe she'd do this, but..."
"Yeah," Cynthia understands. Fucking her best friend's husband was especially bad, but Vanessa had always been messy, inconsiderate, and often cruel. Not to mention a slut.
"So, what are you going to do?" Jade asks. Cynthia sighs.
"I don't think I can tell him," Cynthia replies, "I don't even want to think about it. I just want this all to go away."
"Are you sure?" Jade asks. Cynthia can tell Jade doesn't think this is the best course of action, but she's trying to be supportive anyway.
"I think so," Cynthia says, "I mean, maybe it was just the one time. I don't want to throw away years of marriage over a moment of weakness." Jade's brow furrows.
"If that's what you think is best..." Jade says apprehensively. Cynthia hugs her.
"Thank you for telling me," she murmurs.

She washes her face in the laundry sink and tells Jade that she doesn't think she can stay at the party. Jade understands entirely. When Cynthia heads back out to the party, she sits beside Mark and casually tells him that she'd like to go home.
"Sure," Mark says noncommittally, "in just a bit."
He goes on chatting with their friends for an hour before they finally head home.