Am i the worlds dumbest b/f?

Absolutly not!!! I hate to break it to you hunny, but this guy seems to have played your girlfriend right into his crummy hands ;(. You see, when you express concern like that, girls take it one of two ways. We get it and leave the guy alone, or we want to see what he is "really" like and usually get sucked into his trap. Texting is fine between friends, even when they work together all the time, BUT, it is not normal to sign off with any kind of love statement, i.e. I love you, love ya, love ya lots, xoxo, etc. And when she doesn't want you reading them, that means that there is something that she does not want you to see, especially since these outbursts are new. I would normally tell you to talk it through, but since you have tried and nothing has came from it, I would just go ahead and tell her sorry, it's done with. Need anything else, just ask!