I couldn't bring myself to look back at you as you walked away.
Literal
Leave going you [object-を] I [topic-は] look-back [nominalizer-こと] [subject-が] couldn't-do.
おまえ (you, rough/intimate) and 俺 (I, masculine rough) set the tone — this is emotionally raw, intimate language. 立ち去る (to leave/walk away) and 振り向く (to turn/look back) are vivid compound verbs. ことができなかった (couldn't do) expresses inability born of emotion, not physical limitation.