Nuvaring

my period is 2-3 days late, so I'm not super worried YET...
I got a Nuvaring on December 8th for the first time, and about 10 days later I had intercourse. Unfortunately, he didn't warn or tell me... until afterwards that he had finished inside me... 
and I'm wondering if pregnancy is a high probability, since I had JUST started birth control. I have spoken to him about this and I told him he has to be more responsible... (seriously... wtf)