When you say to him "I love you," understand that you're saying this to someone who is reptilian. I'm sure he performs in the way a boyfriend ought to superficially, but this is someone who acts on impulse. This is someone who, under pressure, cannot love you in the moment and threatens violence against you. He cannot control his feelings.
All physically violent men start out at first as emotional abusers. It will escalate.
You laugh because your brain is at a paradox because while the actions are absurd, your brain knows it could become credible one day. It's nervous laughter in the face of insanity.
Don't care about what happens to him because he clearly doesn't care about what's happening to you. It's all about him. Even after he's been abusive to you, he's got you thinking it should still be about him.
Contact your family, at least tell them your situation and how it might not be safe. See what their feedback is and what they're willing to do to support you at zero hour.
Two years is awhile to be with someone, but don't make living with an abuser five years, or ten. And that's who he is–a violent abuser. You didn't "fail" because this guy baited you in and then started to turn on you. If anything, leaving a relationship like this should be considered a personal victory.