I think it's confusing because it's really hard to face sometimes that people we know well, whom we trust and think are good people, who would never do that, are capable of abuse and violence towards us. That's not a fault of yours. You are not a "lemming" for being confused by that and please don't blame yourself for any of this!!! It's not your fault someone you loved and trusted betrayed that trust.

I am definitely echoing the other commentators here in saying please stay away from him and cut off contact. He hurt you, he crossed your boundaries, and he pressured you to have sex when you did not want to. Even if he's never showed that behaviour before, it's abusive, and it could happen again or escalate. Don't feel bad for cutting him off and doing what you need to do to ensure your own safety!