I dated a guy like that a few years ago. I felt used and he strung me along for a while, untill things weren't going anywhere. So I dumped him. Eventually I realized that it was NOT a normal relationship or person I was dealing with and he had some baggage that I didn't need or deserve. Luckly to say I moved on a new man a few months later.
The bottom line here for you is that you need to hold yourself to a higher standard. Don't EVER let any chick drag you along like that. Remember a real relationship is one you don't EVER have to 2nd guess or question on BOTH sides! Also ...Write down all of the things that you want in a future wife, and don't ever deviate from those goals. Eventually you will find the right one.
Going back to your story...because of the fact that you did the "we are just friends" from the begining is WHY she's acted the way she has around you. Honestly, that would piss any girl off. Especially when the guy doesn't explain himself OR why he's doing those things.
It's not that she used you, but she's reacting to you that way because she probably felt used to because of your insecurities with your past relationship and your sleeping with other female friends.
I'm almost sure that it was NOT made clear to her of your issues with your past relationship that you acted that way. It probably would have been best to cut her off when she started questioning the "status".
Plus you NEED to stop being anywhere near her...you are essentially a "doormat" to her. She will test you and flirt with you and use you, because you are allowing it. You also need to understand that you are not going to have the relationship you want from this girl...all because of the way things started. You invite her over to hang out, and she continues to pull your strings. Obviously that's NOT healthy for you? Right?! The longer you allow this to continue, the more miserable you will be.
As far as counseling...you aren't married or together, however you may want to consider going yourself to heal whatever wounds you might have from your past relationship.
Another thing to remember is that once you have dated or slept with a girl you really can NOT be friends with her anymore. With the way she's acting towards you, she knows that she can use you for whatever she wants...and unfortunately it's not going to change with her. With this girl, think of it like this....she's fishin and keeps pulling back on your reel while you the fish keep going for it. Eventually, you will have to move on as the bait gets old.
I think at a point she did like/love you in the begining, but it's become more of a relationship of convience to her than anything else. If that's NOT what you want...and clearly you aren't getting that out of her...cut ALL contact. Which means, changing phone numbers, deleting and removing everything that reminds you of her, starting fresh, and most of all avoiding her. Also tell your family and friends that your wish is to have zero contact with her, and if she makes contact with any one of them...ask your fam/friends to give her NO information about you. This will help you in the long run.
Also when dating a future girl, telling her about what the "status" is will make her feel a lot better about things...instead of just assuming.
At this point, you need to cut her loose and have NO communication with her in order for you to get over her. Remember that first impressions are everything in a new relationship, so heal first before you get into another one.