Typical "woman gets bored and acts all dramatic to get a break up and then starts dating other men" scenario. This is kind of why I stay away from dating women, unless you're perfect (or have money) they'll most likely get bored and leave you for the thrill, unknown and excitement of a new relationship. If I were you, I'd try to stay away from dating, you don't sound as though you're seeking a rebound relationship (which is good), but if you ever feel as though you are lonely you shouldn't resort to trying to find another woman.
It sounds as though you may have depression and I'd see a doctor about that. That would be a reason as to why you feel as though you have lost who you are. If I was in your situation I'd try to take it easy, I'd try to keep my life fairly stable and without much drastic change until you regain a hold on your life (idk how easy that would be as you may be a student or something). I'd prioritise fighting off any mental illness which she may have caused you and then rethink how you want to go forwards in life as to learn from your experience. I would also try to do new things in my life to try to rediscover some of my old interests (especially if you feel as though you've lost that sense of who you are and what you want from life).