Hi --I know that you said that couple's therapy is out of your budget, but I'm wondering if you've looked into low cost options: Non-profit clinics with student therapists or have a sliding scale, Family Service type of clinics, etc.
Because --while I can offer some suggestions (I will), her behavior of cursing, storming out, etc, is going to make it very difficult for the two of you to talk out issues. It seems that you do need someone to mediate and help.
Essentially she needs to understand what you wrote above --you need to know when she actually is talking to you AND you need the volume turned down on her talking to herself. But, she won't stop if she doesn't understand what your experience and feelings are.
Here's some tips for communicating:
1. Use a lot of Empathy and Validation:
Empathy is where name the feelings you see that her feeling, validation is where you give support to him for those feelings: "I know you were frustrated when you were talking to me and I didn't respond," or "It was upsetting for you when you thought I didn't care what you had to say."
Validation: "I can understand how that would make you mad." or "I can see why you have been getting frustrated by our communication."
Empathy build connection and trust --the greater your trust, the more likely she is to be honest with you. Empathy and validation do NOT mean that you support a particularly behavior, nor does it mean you would feel the same way or engage in the same behavior. It simply means that you can look beyond your own feelings and understand what is behind her feelings.
2.Use "I feel __________, when you _________" statements. Some examples:
"I feel confused when you are talking, I don't know if you're talking to yourself or me." Or another variation, "I worry that you are not interested in trying to work out our relationship when you storm out of the house."
The "I" part of the statement puts the responsibility on you (and hence is less likely to make her feel defensive), but the "when you" part identifies the behavior that is confusing, hurting you, concerning you, etc.
It's much more likely to get an honest answer than a "why" question (Why do you act this way?) which makes people naturally defensive.
3. Use Open Ended Questions: They tend to start with What, When, How, and Tell me: "What is going through your mind right now?" or "Please tell me what your current thoughts are about how we can improve our communication." Or "How can I be supportive of you ?"
Avoid closed ended questions: "Don't you think you shouldn't talk out loud to yourself?" Open ended questions invite conversation, closed ended ones tend to shut it down.
Please feel free to follow up with me using your own specific example ----I'm going offline in a short awhile but will be back later.