As San’s wrote, you know much of this addiction and how it operates. It is never truthful and it is only out to get the next fix. Unfortunately, unless the cg is active in their recovery really wanting to stop gambling there is little anyone can do.
My father is a cg and I know from a very early age what this does to a family and how this addiction tears deep in a family. As you said there is little you can do to make anyone stop gambling, but there is much you can do to take care of yourself. I went years turning the other cheek with my father’s gambling and in the end it really nipped me. I suffered much and so did my family. This addiction just keeps on snowballing until it is either stopped, by not enabling or until it destroys the cg and often this includes the family. Your parents will always be your parents, but they are not entitled to ruin your life. Hopefully you have not enabled them as this will only allow the addicton to grow.
It seems everyone has an addiction these days, so don’t be too hard on yourself. In time the right person will come in your life , I think it is best that you just focus on you and being happy.