Both your brain and the porn are working as intended. It's hard for some people to realize that porn is a drug like any other, that you get self gratification from it like any drug and yes, you can get addicted. This addiction can present itself in many many ways, not all of them will be as harmful as completely killing your will to have real sex, but it can happen.
There are two conflicting discourses that are popular in our current time. One saying that porn is actually good for you, that it gets you to discover and explore new things, that it's liberating, etc. And the other saying it's actually the opposite, that you should avoid it completely.
Thing is, just like any drug, the frequency and amount will be key factors to what negative impact it'll have in your body. Quitting any drug is hard, but sometimes it's neccessary.
As an addiction, you put a considerable amount of your thoughts and free time into using that drug, the primary thing to successfully rehab yourself is to occupy your mind and your free time with something else. You can go out with friends, go to the gym, run, binge watch movies or TV shows, start playing a new game, all sorts of things.
The act of downloading and watching porn becomes just an habit after some time, you just do it and that's it. That's until you stop, then you'll definitely feel super important, you'll feel like you're missing out on good porn that you might never come across again, all sorts of thoughts like this.
But just like any habit, it's just a matter of consistency and time. Whatever you pick to override your addiction, make it something you enjoy and are able to do with the same frequency that you watch porn.