40 years of life, you're not "quitting" this anytime soon. You can quit hoarding porn, you can quit being a weirdo stalker, you can quit being insecure, but you will never cut this part of your brain out unless you literally get a lobotomy or become a eunuchs.
The most important part of my experience has been the ability to "balance" this part of me with my "normal" life. The being 400+ pounds, the gaining, the fetishism, that's not easy to live out for everyone who gets off on it because it really is straddling fantasy vs what is actually something people want to do along with everything else in their lives (get married, have kids, have a job, travel, etc). People want to be huge but also want kids so what do they do, they can try to do both, or figure out how to live with that desire in balance.
For me, "balance" has come through just talking about this thing soberly with a few key people in my life over the years, be they one-time encounters, or life partners, or a platonic like-minded friend, talking SOBERLY about myself and my experience with those people who were open and willing to hear me out has been absolutely freeing. Freeing me from the shame and the guilt and the disgust I had for myself for something I literally couldn't control.
That's just my experience, I do still wish there was more access and more places online where we could be more sober and open but those spaces are either vacant or non-existent. Not to say a Bash or something wouldn't be the place, I've never been, but the hook-up factor is something that would need to be overcome since we're all also deprived of an actual sexual encounter where this is celebrated vs hidden.
Anyway, everyone's different. Remove the shame, make a friend.