A/N: This story is dedicated to BadassGenius, because she asked me to write a Mark/Derek fic (although it's also Addek, but I'm sure she won't mind) and because she always has wonderful words for me.

Derek was feeling numb. The previous week he had found his wife and his best friend in bed together, and now he couldn't do anything. He slept all day, and ate a lot of junk food. He didn't even go to work. Addison's room was a taboo. He had made clear she knew he wouldn't go in there, or that he wouldn't talk to her if it wasn't necessary. He couldn't stand her presence. Too bad she was always in his thoughts.

He lazily turned off the TV, growling as he stood up to get the door. His first instinct, when he saw Mark, was to slam the door in his face – and possibly hurt him and break his nose.

But his friend – or ex friend – put a hand on the jamb, preventing him from doing it.

"My wife is not here." he said angrily.

"I know, I didn't see her car. But I didn't come here to see her anyway. I'm here to talk. To you."

"Well, last time you talked to my wife you screwed her. Or did you make love to her? Because-"

"Oh, Derek. Whoa. It was just... you know."

Derek punched the wall hard, and a photograph fell down to the ground. He glanced at it sternly, knowing that it was his wedding picture, the one where he and Addison were cutting the cake together. He pounded it, and broken glass dispersed over the floor.

"It was her favorite one." Mark commented.

Derek walked to the kitchen, opened the fridge and took a fresh beer, drinking half of it in one big sip.

"Get out Mark."

"I'm not going anywhere until we fix this Derek. You know we need to. And we can."

Derek didn't think they could. Not now, anyway.

"Let me say something." Mark continued when Derek didn't answer. "You always neglected her, Derek. All the dinners you had to attend to? You never went. Your anniversaries? She was alone. You were at the hospital most of the time. So – I'm not trying to excuse her or myself – she had a reason to turn to me. What we did was so wrong, but we missed you and we made a mistake. That's it Shep."

Derek nodded, taken aback by his words. He never did that. He was sure of that. Why would he ignore his own wife? His wife that he loved? He was sure he never did it. Except, he wasn't sure at all.

x

"Mark is coming over for dinner." he told Addison harshly when she came home. "He will bring pizza."

She nodded, unsure of what her answer should have been. "Okay."

"Happy about it?" he smirked. "Your dear lover will spend some time with you. I could even leave you alone for a while... If you're lucky."

She let her bag slip on the ground, as burning tears started to mark her face.

She stopped. "What happened to our wedding photo?" her voice died down.

It was a rhetorical question, and it was like the final strike. Her marriage was over, it was her fault and she couldn't save it in any way.

Derek's acid answer never came out. It stayed there, stuck on the tip of his tongue, fading. When he saw her so broken, he felt his own heart cracking.

He walked by and embraced her tightly, inhaling the good smell of her hair.

"Sorry. Sorry. I'm sorry." he kissed her neck, sobbing almost as loudly as his wife.

Addison could feel her heart explode. It was the first time her husband held her in over a year. With a waterfall of tears and a deep breath she could finally clam the pain.

A/N: By the way, I realize that Derek is a real ass.