[...] dir selber leid zu tun
Comes from sich selbst leid tun which is referring to Selbstmitleid (self-pity).
Your sentence means:
Could you please stop feeling sorry for yourself?
selber is rather colloquial, selbst would be more "standard"/formal. But both mean the same, in this case yourself.
Leid can have different meanings depending on the context. In your case it refers to rather to pity than to harm or suffering.