What is the solution to the problem of practicing masturbation and watching pornographic websites, along with feelings of guilt and fear of falling into the forbidden?

You must repent to Allah from masturbation and watching forbidden things. What helps with this is the company of righteous people, adhering to dhikr (remembrance of Allah) and du'a (supplication), imploring Allah for well-being, and frequent fasting to discipline desires, as the Prophet (peace be upon him) said: "And whoever is not able to, then upon him is fasting, for it is a wija'" (a shield against sexual desire). Also, listening to beneficial lectures and attending gatherings of knowledge, and closing the doors to corruption. If it is possible to bring the wife [to him] or marry a second wife, then he should do so.