Thanks for your query.Based on the facts that you have posted it appears that you have sustained injury to your Testis during sexual intercourse with your girlfriend.It is practically impossible to separate Epididymis
from testis as it is a part and parcel of Testis.
So do not worry at all It is just a trivial injury.
Any incidence that would separate Epididymis from testis would result in to hematoma
and severe pain
Just take pain killer like Brufen
400 mg twice daily for 5 days. and avoid similar encounters in future.