Hmm. Well, I wish you the best with whatever choice you decide on.
That said.
Have you written the letter yet?
Something I have found helpful is sharing those painful letters and rants n' raves with someone close or who you KNOW will support you.
The reasons being:
*You get to share those emotions with a real live person rather than just having them to yourself or 'out into the universe'.
*You have someone who can help clarify and talk/care you through difficult emotions and sometimes help shift your perspective so you can go deeper
*You have someone to WITNESS and acknowledge how you feel. Period.
The likelihood of this guy to acknowledge your real feelings or treat you respectfully are very very low.
Sending that letter might make you feel crazier in the long term.
Just asking you to think about trying sharing that letter with someone else before sending it, if saying it outloud or burning it or posting it doesn't really cut it for you.
If that doesn't change things for you, you can always choose to send the letter later.
Taking action when flooded with charged emotions has this nasty way of blocking off our options in our eyes and not thinking of the big picture. You know??
You will get through this! And those 8 years aren't all wasted. Not if you learn something, and you are and will.
You chose an experience that can show you that you never again need to settle for less and you never have to be one of those people who stumbles from relationship to relationship clueless to what they are doing.
Now you know. It's conscious choice.