I feel your pain because I was also in 4 years relationship and was left by my bf, it's been 5 months and I am still recovering - it is very hard and I chose not to look for anyone. I also feel that I am not good enough for anybody, maybe this feeling we get is because we were left by a man we loved, man we wanted to be with, man who was good for us. I don't even know how to go back to dating and how you did it.. If you know how it feels when someone hurts you then please, don't do it to others, if you don't feel for Mr. A.H then tell him so he knows about it, if you don't feel it now then you won't feel it later.
I wish I could give you a better advice but this is all I can say, maybe you also need to stop for a while and be happy oh your own.