What is incumbent upon one who broke his oath and vow to abandon masturbation three times, and is indulging in thoughts of intercourse and ejaculation - without pressing on the private parts as he used to do before the vow - considered a breach of the oath and vow, and what are the consequences of that, especially since he did not fast the days he broke his oath due to illness and not remembering the number of times he indulged in thoughts?

Every movement that causes semen to exit due to prolonged thinking or thigh movements is considered prohibited masturbation and a breach of an oath. Your oath to abandon masturbation must be fulfilled. If you break the oath, a single expiation for breaking an oath (kaffarat yamin) is required, even if the breach is repeated. Your oath to fast three days for each instance is an oath that must be fulfilled. If you intended it as a "vow of obstinacy and anger" (nathr al-lajaj wal-ghadab), you have the choice between fulfilling it or offering the expiation for breaking an oath. The expiation for breaking an oath is sufficient if you are unable to fast due to illness.