hi kr1sty,
regarding the cards you can just scratch the 3 digits in the back of the card with a knife or screwdriver, to guarantee the three digits have been permanently removed,
do it without looking, to avoid the possibility of memorizing the three digits, you will not be able to use the card online. and you will still be able to use it to pay at the shops or to withdraw money from the ATM.
similar tips and tricks you can find in this forum, you are not alone. I know what you feel I have been there and done that.
what really works is the following:
1: no money = no gambling, you should find a way to limit your access to the money, if you can ask your partner or a family member to take the financial control, this will solve 50 or 60% of the problem.
2: willpower: you can’t depend on your willpower to stop gambling, you should find outside support to help you stop, you can plan and implement roadblocks that if your willpower failed the roadblocks will prevent you from relapsing.
3: it is a permanent illness, so you have to learn how to live with it, it is not the end of the world, some people are diabetic we are addicts. we can live with it, but as the diabatic should be always careful about what he eats, we should be careful about how we are dealing with money.
I hope you all the best