I'm taken aback by some of the responses here. Relationship violence and getting away from it isn't that simple. The person is not "choosing to be raped", they are choosing to protect themselves from being even more seriously harmed or even killed.
It's a common pattern that fear of what the abuser will do keeps the abused partner trapped in a terrible situation, too afraid and broken down to leave. And that's a real fear, not imagined or exaggerated. Nor is it easily dealt with, even by going to the police or courts. In some situations, restraining orders can be like having an umbrella to protect yourself from a tsunami.
@Valer that doesn't mean you have to stay, it means you have to be very, very careful about how you get away. Please contact a centre that specialises in supporting people who are in abusive relationships, and get help from them. A good start in finding one is this list of hotlines:
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In fact the whole website has good information and non-judgemental support.
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Regarding your nightmares, often our dreams are trying to help us by bringing things to our attention. Do you think the nightmares could be trying to get you to take action against the risk of getting pregnant? While you're in this situation, it's the only way to reduce the risk.
I can understand what you say about why you can't get pregnant. In addition, I'm very concerned about how much harder it would make it for you to escape, if you were pregnant or had a child. Can your t-doc help you work through your feelings about taking it? Maybe if you can talk about it more you could get over the obstacles to taking that step.