That was super disrespectful, and honestly kind of scary. You don’t get to just “assume” things when it comes to sexual scenarios like this, exactly because situations like this happen. 

If he doesn’t really apologize to you, and recognize that what he did was incredibly unfair to you, then I would be very worried about what kind of man he actually is. He needs to take responsibility for this. You have every right to be upset. He crossed a boundary for you, and also invited another man to cross a boundary with you. How can you trust that? If he’s going to take liberties with your body he needs to know for a fucking fact that he has your consent.