Dev, as you well know, this cannot be a tactic trying to "shake her up". You have to be there.
Having followed your situation from the beginning, you may well be, and honestly, she seems very far gone. She sounds very uncomfortable in her own skin, let alone prepared for the demands of a family. She has much work to do over much time.
Your letter sounds so final, and yet so healthy for you.
The only thing that I would change is where you say "I will not be your friend"; change the "will" to "can". It's not that it's your choice not to, it's just that it's not possible.
