Preformed oral sex on bf 1 week ago. We got a cold 2 days later. I got a fever sore yesterday (1 week later). Did he get genital herpes bc of me?

Unlikely. If you didn't have a cold sore when you performed oral sex on your boyfriend it is unlikely but not impossible that you gave him genital herpes. Studies show that some virus can be shed when you have no lesion but it is much less and not as common. Hope this helps.