Ok, I understand. I'm sorry that you've been put into this situation, but what you have to understand is that most of that isn't illegal. The military doesn't and can't pass laws on a person remaining faithful in a non-marriage relationship.
The medical issues are the result of a pregnancy complication. The expenses could have occurred whether or not he was faithful, so while his cheating certainly makes you more cognizant and more hurt about the situation that goes forward, it didn't directly contribute to the injuries at all.
The point here is that, again, there simply is not any law in the military or in the civilian world against a person being, for lack of a better term, a pig.
You can sue him, in civilian courts, for a share in the cost of your medical bills and he was sharing in the pregnancy and, presumably, was acting in a way that suggested that you were going to go through with it, but that is not a military matter. That's a civilian court matter, for you to address with a personal injury attorney.
The military can not and will not give you anything in relation to your injury or the costs regarding it. You were not married. You weren't on military insurance. He was not receiving any specific funds from the military, like housing costs or separation
pay, based on your relationship. Unfortunately, as far as the military is concerned, there was no legal relationship between you and would not be until you were married.
On the issue of his reporting this incident to his command in order to get emergency leave, I do believe that is something that you can report to his commander. No victim, oddly enough, is ever entitled to a specific outcome when they report crimes. Prosecutors (in the civilian world) and commanders (in the military) actually choose what action to take. All you can do here, regrettably, is report the fact that he used that emergency leave time to go meet other women rather than using it for the emergency that he alleged to his commander. That will likely result in him getting into some trouble with his command, possibly including criminal charges.