I LOVED the ending! Here's my analysis:
I thought the ending was great.
This is how I see it:
She left Peter. She's chasing after Jason, who has decided to vanish because he just can't deal with her crap. She's fantasizing about Will, who's being so nice to her, because she's making it up in her head. She was a complete idiot for not snatching him up every chance she got.
No man for Alicia. She's now single.
She screwed over Diane, big time. I'll bet money Lucca is furious at her too for bullying her into doing her dirty work. She's ruined her relationships with two wonderful women who only wanted to be her friend/colleague. Carey is giving TED talks.
No friends for Alicia. No friendly colleagues for Alicia.
Zach is in Europe. Grace will be in CA. She'll be childless too.
Her day-to-day important people have left her, or she's pushed them away. She's still got her mother & her brother who will always love her. Which is a good thing. Grace adores her. Alicia is not a monster, and she's still worthy of love. She's just a bit of a *beep* and like Will said to her, "My god, you don't even know how awful you are!!!"
She'll be fine. She'll go work for Canning, and nurse her hurt feeling by getting a new boyfriend. But she totally got what she deserved in the end!