no you deserve way better!!! the fact that she is saying she doesnt wanna be with someone who is sad all the time, it's her damn fault that you're sad!!!!!! wow this girl needs some serious help and therapy, cuz no one would give that much of their life to someone and not even think twice when it comes to letting it all go.
Does she get mad that your untrusting, cuz it's her fault that you can' trust her!!! she can't blame everything she has done on you, you are justified in the way you feel and she needs to face what she has done instead of get defensive which it's obvious that she is. she stayed with you for so long for a reason though.... i would say leave her completely alone, dont talk to her at all even if she tries to talk to you, make her miss you and think she has really completely lost you, it's the only option or chance you have if you want her back(i dont know if you do)