Flatline is when you feel dead down there. Zero response to sexual things. You don't feel anything towards women even when they are undressed or in a tight gym outfits etc. Your body doesn't give you any physical response. Not even porn interrest you anymore. You also might feel very low motivated and tired in general. Not interrested in things. Flatline hits when it hits. My flatline came right after the day 7 testo spike. Now i'm seeing some good signs and i feel i'm finding my way out. I'm doing my very first nofap after over two decades of porn (and i was into all kinds of nasty fetish shit, like bestiality. I really didn't watch normal porn at all). I'm on day 41.
You really want to rewire with your woman. That's the best thing you can do if you want quicker results. It speeds up the process of healing and rewires your brains to the right direction. It has helped me big time. I've been doing stuff with my woman, sex every other day, cuddling, kissing, hugging... you know, the basic stuff, but more often than usual.
I don't think you're broken. I don't believe your reboot will take years. Months for sure. 6 months? Nah. Few months? Perhaps..
You might want to watch youtube videos from Project Stronger Self. Scandinavian Bob's nofap time line part 2 is from where i find comfort and motivation. My reboot has been following that timeline.
There will be times when you suddenly feel everything is back to normal but suddenly the day after you feel like shit. Just keep pushing yourself forward. Don't test yourself with porn when you feel completely dead down there. Just don't! That is the worst thing you can do.
Day before yesterday was a deep flatline day for me. Everything was "meh". Had sex with my woman, dick was like 80% hard. I had zero interrest. Yesterday my lady came to me and she was in her sports bra and little strings and she asked me if she has made any progress at the gym and oh boy.. what a fucking turn on it was. It came from nowhere, the flood of pure sexual lust and it gave me 100% hard stubborn erection. It was not under control. Not even a bit. And let me point out that we have been together like 15 years and we have many kids. I've seen her naked million times and i'm used to seeing her naked and shit.. but still, could you imagine, she gave me that overflow of emotions and physical response just by asking me if she has made any progress and showing her body to me. That was insane. It really is insane. Where is my old lady i've been living for years and who's this new hot young cougar living in my house?!?
this is the power of reboot god damn it!! But anyway..
Like Gabe says: Porn is the problem.
Don't go back to porn, not to even test yourself if your dick works or not.. it does work, and you are on a healing process.