More advice for next time since the ship has sailed but never admit fault. Insurance is going to sort it out anyway so what you said to the guy doesn't really matter. If you said it to the cops it's another story.
If you were rear ended it's not your fault period. Even if you slammed on the brakes and came to a complete stop they were following too closely. Obviously this doesn't apply if you changed lanes in an intersection or something.
Anyway yeah my piece of advice to you is always look where you are going to put your car before you put it there, check your mirrors more often, and if you can swing it get a dash cam. If your trunk won't close and you can't afford the repair it's probably just bent in a way it's not supposed to and you might be able to beat it back into shape with a 3 pound sledge