I am thinking that you are:
1. upset that your girl is hurt and that even though it was NOT your fault, you feel doubly awfull that you caused it.
2. irritated that your girl blames you even though CLEARLY it was not your fault.
3. tried to diffuse a really awfull situation with humor and instead of that result, fanned the flames...
... just an all around shit situation that neither of you asked for, but landed in your laps anyway.
Welcome to life.
Whether a couple is impaired for good (meaning the integrity of their relationship) or they move ahead having become a more unified force is just a question of life. I am thinking better to find out when the relationship is relatively young then way down the road after many years, home, family, etc comes a long.
Sorry that this happened to you both.