Mixedup Emotions, I would say it was perfectly fine to send that email. Don't worry.You were able to express a lot of important stuff in it. If your T allows you to email then whatever you send should all be regarded as part of your 'treatment'. I used to do a lot of emailing my T and I also used to get angry and frustrated at myself, the past and the little girl inside me. I eventually learnt that none of the past was my fault and I learnt to be gentle and compassionate with the 'little girl' part of me.
The other thing that helped me is journaling - writing out all the anger and frustration.
Take care and I hope you will get through this painful bit soon.