What is the sensation the questioner feels when masturbating, and does it necessitate ghusl (ritual bath) or only wudu (ablution)?

The sensation of pleasure upon masturbation is what determines the necessity of ghusl (ritual bath). If semen is discharged with pleasure, ghusl becomes obligatory. However, if the fluid discharged is madhiy (pre-seminal fluid) (without pleasure), then only istinja' (washing the private parts) and wudu' (ablution) are required. It is obligatory to immediately repent from this bad habit by ceasing it, regretting it, and resolving not to return to it.