1. You have not mentioned whether he had promised you marriage or not for which you agreed for his proposal to have s*x,
2. If you had consentual s*x with your BF, then you have no reason to agitate for your physical problem derived from both of your s*xual act,
3. You two had no legally acceptable relationship. If he now wants to break up, he is free to do that legally though civilised world expects him to be by your side during your present traumatised days,
4. Unless it is a fact that you agreed to have s*x with him with the promise of future marrisge which he is denying now, you have no valid legal ground to agitate for.