Re: Feeling financially used by wife.
Yes! I am in a similar situation except I only make 30% more than spouse. But it is very important to me to keep finances separate as I have kids from a previous marriage, and I don't need to partially support a 50 year old spouse with $ that could go towards my children. (Note: my spouse has a history of being irresponsible with money)..
So from day #1 I **Always** file "Married filing separately. It works great for me! YES I am more heavily taxed by filing "Separately". But I don't care - I never have to be responsible for another adults taxes, especially an adult who has been irresponsible (he even called my mom 6 months into our marriage to ask to borrow $ from her)
If you let her know at some point you will be filing separately, if she complains you can nicely say "well honey, I need to (save for retirement/save for home repairs, exc.)....we both filed separately before we got married.....if your wife were to continue more, just nicely say "honey, just make sure you get a good accountant and you probably won't owe that much" Just be blasé
And yes -- about asking her to pay 1/7th of the bills -- that is totally fair. If she balks or asks why, say something like "Well I want things to be fair" or "I've got kids to save for/medical bills to pay/retirement to save for" exc exc