It just sounds to me like you guys spent too much time together and she wanted some space. Yet when you gave it to her, she would get desparate and feel like she is losing you and want to be back. It sounds like me in my relationship, I had some serious issues and when I wasn't like I was with my girlfriend before, she freaked out and got really upset and tried and begged and pleaded to get it to work. That neediness made it worse and I really backed away and she tried for months until she got sick of it and kicked me to the curb.
It's really hard to grow as a person in a relationship when you are there to be their crutch. She obviously has some issues and with you in the picture all the time constantly being there for her when she would get desparate, she didn't really grow or learn much. She had you around as a cushion until she was ready to drop the bomb. I understand that you are angry and frustrated because you care about her so much and had so much invested in her. But the fact of the matter is that she isn't communicating to you and isn't being honest with her feelings. I remember that when my ex dumped me and resisted all my attempts to get back, I began to tell her everything that was going on with me finally and it poured out of me like a floodgate. Of course that's the wrong time to try and fix things and it must have been unattractive as hell. Now she's with another guy. That's when she was finally ready to kick me to the curb when she had him lined up.
It's great that you tried to help her through all her problems, but you have to pay attention to what you are doing and if its getting results. If it isn't, why would you continue to do that? Because you loved her, right, but there is only so much you can do and if she isn't willing to work on and become a better person herself and just wallow in her self pity about her issues, nothing will ever be fixed. I'm sorry it had to end like this for you.
				
			 
			
		 
			
				
			
			
				Waking up next to a beautiful girl,
Step outside and say hello to my beautiful world.