I read through your entire post and it sounds like you are getting stronger through this, well done. I am working on that also. I have a different post going on another issue, but similar facts to yours.
I wanted to read up on some thoughts of this no contact ie. let her pursue you angle, and you have had some really good answers posted here. I am working on that.
But to toss you some advice your email to her is too whiny (as I work on eliminating my whininess).
Take out the $100 rent part, keep it professional.
"As you are aware your monthly set expenses are substanitally less than mine from a housing standpoint. I believe it to be equitable that while I am covering most of the expenses related to this residence, that you continue to contribute to the utilties".
TBL now equals "Toward Better Love" M-44 W-42; 2 kids; married 11 years 1st bomb 10-08, reconcile 12-08 2nd bomb 8-09, moving toward reconcile 3-7-10