Dating is the least of your worries. You must tell someone as soon as possible. She is only thirteen. Someone needs to be brought to justice and she will thank you later.
Losing this relationship is a tiny sacrifice compared to what she can lose psychologically. Do you know who did it? If it is a family member go to the police but only if you know that it really happened and please don’t take this the wrong way but your only being thirteen probably proves that you will have many relationships in the future no matter how much you might think she loves you now. The point is your natural maturity is going to be dwarfed by her forced maturity. Maturity, especially sexually, has been forced on her, a shift in her emotions and physical awareness will start taking place and this is not something that you can handle at your stage of development.
I am sorry, that is psychological proof. I am not trying to dismantle your masculinity or your maturity. You could be very mature for your age but there are sociological things that you have not experienced yet that are necessary in order to really help this girl. She is also too young and traumatized to know what is best for her.
Exercise maturity and contact the police if it is a family member and I am painfully sorry that you have to undergo this, both of you. Your youth is being violently ripped from your hands and it an inexcusable shame.