Wow...I'm going through a situation kind of like this.
I've done a lot of the same things you have; silent treatment, mysterios one-liners, etc. They have worked pretty good, I must say.
So...maybe I haven't read carefully enough, but are you open to the possibility of dating her again, or not? Are you completely over her and want nothing to do w/ her, or do you want to give her a chance again (at some point) and see if she can be more stable?
If you choose to get rid of her entirely, it's pretty simple. Just move on, tell her to fvck off, that she screwed up, etc. Or you don't even have to tell her anything, just don't respond to anything she says or sends you. However, be prepared for her to barrage you with messages and such for a while, until she gives up.
Giving her another chance is a bit more complicated. See, you have an attatchment to her obviously, on some level. But she did screw around with you- and with girls, if they screw you one time chances are they'll do it again. So there's these conflicting feelings. So what I have planned out for my similar situation is:
1) -Improve my life- When I was with my gf, I neglected lots of things in my life, especially making a social life here at college. I need to get a good social life going again. In addition, I'm going to work out everyday and improve myself physically, as well as concentrate even more on my academics. I'll make time for more fun stuff too. ** This helps the situation by giving you other things to think about than this chica, and gives you more confidence, more ability to securely say "I don't need her...let her make me want her"
2) -Get more options- Becaue of said social depravation, I don't have many dating options to speak of at the moment. I'm undergoing a personal boot camp of sorts now, as I've never in my life been one to do cold pick-ups. I'm going to increase my options. ** This helps for several reasons: like the above, it gives you other things to occupy your mind. Additionally, it's always more condicive to good decision making when you have options to choose from...you'll be able to compare, and really decide if this girls all you thought she was. Plus, the jealousy factor from your ex-gf knowing your dating other chicks will help her IL tremendously.
3) -Raise and maintain her interest level- This doesn't require as much effort as you'd think- it really only involves restraint. For example, when she starts messaging you, you feel a desire to call her up and have 'the talk', and get back together. However, this would be counterproductive- in my experience, even though she may agree after having the talk, she'll later have a 'backlash' and start thinking about the reasons she broke it off with you in the first place, and she'll break up w/ you again. So...now that you know she has the initial interest, you need to restrain yourself and hold back from contacting her. Keep your communication with her brief and sporadic- don't initiate many contacts. Then, after a period of time (2-3 weeks in my case after she starts contacting you) call her up rather spontaneously and have her accompany you to a fun activity (bowling, etc). Have fun, and drop her off after a relatively short outing, no kiss at the end, no matter how much she wants it. Hang out w/ her again, and do something fun again- this time walk her to her doorstep at the end of the date, but only give her a hug.
** This should steadily raise her interest level by doing all of the things women find attractive- you're becoming a challenge, a hot commodity among women, fun and spontaneous, and a little bit mysterious. AVOID any serious conversation about a relationship between the two of you at this point.
3) -Decide if you want to continue, and if so, make a move- Evaluate if she's still worth spending time with. Compare her with the other chicks you've been going out with. If she still strikes you as appealing, then you can make a move. Don't have "the talk" here- just take her out again and really build up the kino- possibly have the outing be slightly more serious than the first two. Then, walk her to her doorstep at the end, and just kiss her. If she doesn't accept it, just walk away- you have options and a life, after all. If she DOES accept it- then you're in most likely, but DON'T have the talk right there. Just bow out and leave. Keep her wondering and in suspense. **When you're evaluating her worth to you, look at her interest level. You want a woman with a high, steady IL. Look for this in her as a good indicator of her worth.
4) -Non-exclusive dating- Assuming you kissed her in #3, she'll probably soon be badgering you about "Are we back together?" etc. Here, I suggest telling her you're open to the possibility, but, given past circumstances, you'd like to keep some doors open for a while before making any BIG decisions. And this is the truth- you need some time to evaluate her against the competition. If you've gone through the previous steps and have raised her IL, this will drive her NUTS!
5) -Whatever happens next- I wouldn't suggest that you be the one to make the two of you exclusive. Leave that to her. When she asks you, really think about it and decide whether, after all of this, she's still worth it. Then have fun with whatever your decision was.
Well- that was long and maybe too specific, but that;s my personal plan, and I think it's a good one. Obviously you'll need to tailor it to your own personality, but it's a good reference point anyways.
If you want to entertain the possibility, and you do the above, you should have a refreshed relationship. And an improved life outside of this girl to boot. Win-win. Synergy. Lovely.
Hope this helps- E-Z