"I haven't got time to hang out with you." "Aw, now I'm bummed out…"
Literal
You [with-に] associate extent free-[subject-じゃない]. / Somehow dejected is-[yo-ぉ].
A quick exchange of brush-off and mock dejection. ~ほど暇じゃない ('not so free as to X') uses ほど as a scope: 'don't have time to the extent of doing X.' しょぼん is a casual internet/youth mimetic for feeling let-down or sad — often written alone as a reaction. The stretched よぉ adds cartoonish disappointment. なんか ('somehow, kinda') softens the feeling.