First of all, I’d just like to state that men don’t “loose their virginity.” Men just “do it for the first time,” kind of thing. Unlike women, who actually have a biological way of demonstrating that they are in fact virgins or aren’t, men do not. So, men simply “do it for the first time.” Though, it is very understandable as to why you’d say that you “lost your virginity,” being male. That phrase has been started to be applied to men, too, in the recent generation, which I find silly. But, as Jim Rogers says, it’s better to embrace change and use it to your advantage, than fight it.
Anyway, you need to make it clear to your girlfriend that you’re in it for a romantically platonic relationship of chastity only, in my opinion. You need to tell her that what you both did made you feel horribly spiritually, and it totally severed your connection with God…etc. She has to understand that if she wants to continue dating you, to the point of marriage and beyond, you will have to live in romantic relationship of platonic chastity with her; and, she will have to comply with such, too. Let her know that it’s part of of your faith, being a Catholic. Hopefully, she will understand and at least succumb to it in the long run, so your relationship with her can continue; because it seems that you’re very content with the strong relationship you have already developed with her. And, if it turns out that she doesn’t want to honor the way you want to live in the relationship, then it will have to end.
And, remember that if you love God and are Catholic, you WILL be willing to give up everything for Him.
And, I’ll add you to the people on my Rosary tonight, and for days to come. I’ll pray that your relationship with her turns out for the better, as you want it too, Jack.