Hi Simon and welcome. Well done on looking for help.
I like the heading of this thread ”This time I mean it”
The thing is of course you, like I did, have ”meant it” many times in the past.
You hae recently got engaged? Congratulations. Does your fiancee know about your gambling? Or that it is a problem?
Has she heard the promises that you mean this time before?
It’s an old saying – actions speak louder tahn words. My family had heard all my promises, came a time they didnt believe any of them. When i started doing things though, getting to GA meetigns, making myself accountable so i couldnt gamble secretly etc well, then they had cause to think ”Hey, maybe he means it this time”
The actions that will help you stop gambling are the same actions that might help you rebuild trust etc
What positive actions are you taking?