I just want something more solid, a stronger motive and reason for OP to WANT Reeva dead.
I don't believe actually wanted her dead .. just that he lost his rag with her, and in a fit of pique, he shot one shot at her through the bathroom door .. then immediately realised what he had done, so he had to finish the job off, just so that she couldn't speak or be a witness to the event (remember, after the first shot he would've been aware he had hit her, but wouldn't have known the extent of the injury or whether she would've been able to survive it .. so he continued shooting until she fell silent).