help with communication

In general my wife and I get along very well, enjoy each others company and truly love obe another. But we have the hardest time communicating with each when it comes to issues we may have with one another. More so when I have an issue I want to discuss an issue I have with her.
one of our biggest problems we have is our financial situation. Before we were married she already had her degree. I was close to completing my degree but still needed to go back to finish. For the last three years, I've been working my butt off at the best job I could get at the time. Shes had a job she puts in less than 10 hours of work per week and barely makes enough to pay fir the gas she uses. Before we moved in together we agreed on splitting the bills so that I pay rent, she pays cable electric cell and food which should cost about 25% less than the rent.
Since day 1 of living together she never held up her end of the agreement.
Ive tried to talk to her time after time again about the financial strain she is getting us into. Ever time we (I) attempt to have the same conversation with her over and over again it always ends the same way. It turns out into a big fight, she says she knows she has no other choice but to get a better job just to shut me up. Once the conversation is over nothing ever changes(I mean I had her go with me to a job fair for both of us to try to find new jobs at that we planned on going to a few weeks before the event and the day of the event she "couldn't find her resume."
I know that any conversation that attempts to acuse or single her out will never accomplish the intended goal for having it. She shuts down at that point. But I cant have a conversation when it comes to situations like the one above without doing so. How can you? Then I get to the point of becoming very angry at how the concersation is turning out because of the lack of acknowledgment and taking responsibility for her own actions.
now, because of our history of "adult" conversation our lines of communication for negative events are practically nonenonexistent.
How do I do better at reopening our lines of communication and how do I go about bringing up the issue I described above yet again as were still in the same situation.?

Wow, that is a tough one. What about a budget? So this is something tangible, not something she can dismiss or not talk about. I could see this happening like this. You prepare a budget - it doesn't have to be too fancy or even finished, as this is something you will hopefully work on together. Instead of coming at it from a negative stance you could say that you wanted to plan a holiday together and budgeting is a good way to set up a savings plan. This is not too unusual, tons of people do this. Talk about where you might go together, places you have always wanted to travel to or visit a family member or whatever. it should be a happy experience. Then say 'we need to work out together how we can plan for this to happen.' Take it from there.