What should a girl do who became addicted to watching pornography, then quit, only to return to it again, and now feels compelled to watch it, experiencing accompanying physical and psychological symptoms, and wishes to be rid of this situation?

The door of repentance is open, so hasten to sincere repentance, sever all ties with the sin, resolve not to return to it, and be sincere to your Lord in your repentance. Do not tell anyone what occurred from you. Increase in acts of obedience, associate with righteous women, and adhere to remembrance and supplication. If you return to sin, do not despair; rather, repeat repentance no matter how often the sin is repeated. As for the fluids you mentioned, it appears to be madhy (pre-seminal fluid), which is impure and necessitates istinja' (washing the private parts) and wudu' (ablution).