Is anyone else really annoyed at Naomi. Seriously, Sam is your ex. You no longer have claim on him. It is not wrong or selfish for Addison to be with him. The reason she didn't tell you was because she knew how you would react. She knew you were going to overreact, and you did not prove her wrong.
I understand your reaction in one sense. You cannot help your emotions. You can, though, help how you deal with them. And lashing out at Addison or letting her know your feelings, especially the way you did, is just not okay. She did nothing wrong, so while you can't help being angry, you need to stop taking it out on her. Especially considering you aren't blaming Sam at all or getting angry at him.
Gah, anyways, I just needed to express my annoyance, and I found this community while looking for somewhere to express it. We really need a community like the Grey's one where we discuss episodes and stuff.