Since you are co-workers I would suck it up and act like a good co-worker. I wouldn't really too much about the friendship part, but since you work together you guys need to at least be polite to each other and stop the drama.
if you have gone to your boss, and your boss has done nothing about her behavior at work then you have your answer. Your boss does not care that she comes in late and leaves early, and that you are pulling her extra weight. At work try to find a way to do less of her work. If you have not gone to your boss or HR then I would do that now.
As far as the friendship goes, I would institute a policy of not being FB friends with co-workers. Let your friend know that and ask that she contact you over e-mail or text instead of FB.
As far as the texting goes, I am not sure what to tell you. Personally i might respond with a "been busy etc" message. If you've already gotten into it with her 2-3 times then saying anything else won't matter. Just keep your distance and maybe she will get the hint, but don't forget to be polite at work. Its really hard ending a friendship in an adult civilized way. I've had to do it a couple of times, but believe me its way worse than the whole crazy blow-up never speak again ways to end a friendship. And since you are co-workers you really need to be able to maintain some level of a friendliness even if you no longer hang out outside of work.