Does the emission of pre-seminal fluid (madhy) – without semen or arousal – constitute a breach of an oath after swearing to abandon masturbation, especially given the inability to expiate the oath?

If "I do not perform masturbation" means not discharging semen, then the discharge of prostatic fluid (madhy) is not considered a breach of the oath, whereas the discharge of semen (mani) is considered a breach. Masturbation is forbidden, so one must repent to Allah from it and not return to it.