The slyest excuse

So hello guys. I'm going to talk about something that probably all of us have experienced but lemme start with a brief introduction. I'm a guy in my late 20s and have been masturbating for 15 years now. It was some 7 years ago when I first realized how badly these actions were affecting me and made my mind to quit. And been struggling for all those years. My longest clear streak was last summer when I made more than 3 months. Yes, whole 3 months and a few days more. I could hardly believe it. I was motivated by the 90-day rule from this forum and managed to stay clean all while going to the beach daily [TRIGGER WARNING] where there are many topless women in thongs. I don't go there for people watching but for recreation and sea swimming so don't wonder why I kept going.
The summer streak actually came as gradual elongation of my efforts. Usually when trying to abstain I could make no more than a week, like from weekend till the next one. But in 2017 on two times (spring and autumn) I made two-week streaks motivated by certain life events, as I recall - all on crude willpower. Then last February I managed to make a month starting with fasting and daily meditation for the first week at least. So the summer came quite naturally.
I was planning to write a success story here on 23rd of September but short before this planned date, right after the end of the active season when the weather went bad and I stopped beachgoing I slipped and then relapsed. Sinking steadily until 2-3 days ago.
So - for all these years of struggle. As with everything there are many factors but there is a certain mind process that's been sabotaging me more than anything. It is the excuse that since I'm going to quit now I'll have one last binge. Just one more and it's over. As u can imagine, I've had probably thousands of such last times..
I suppose many, if not all of you, have struggled with such dellusional excuse - even though you know the theory as your hand, keep failing at practice.
So I'm gonna ask for help on this one from those of you who have had success after all - how did u get around it and what tips and tricks could you recommend to make at least another long streak?
Sadly, with such mindset telling myself I'm quitting now forever seems like not a very good strategy, however much I'd consciously want to make it a reality..
However, this 'last one' seduction comes even if I tell myself I'm going to abstain only for a week. Like: 'A whole week? That so long, better have one last so you don't miss it. Watch till you are totally bored and unaroused so those images don't haunt you during your streak, it will be easier for u this way.' Of course it's not. On the contrary, the more images I absorb, the more appear in my mind even if I'm not physically aroused. It's a vicious cycle of dellusions but how do I break loose..? Maybe one thing that could help me is visiting this forum daily in search of inspiration. I hope I don't get banned, given my sometimes emotional responses.
Anyway, the more ideas and strategies, the more weapons in my arsenal. So I'd like to hear what did work for you to make the last time be last for real?