1- Accept the truth (What's happening to you) , and just deal with it:
When you lose a lot of money then you must accept this loss, and overcome it, without blaming yourself or something else, because that does not change anything.
Then, you must deal with, by compensating the loss, you can even start a new business field.
2- Control yourself:
The most essential thing is how to control yourself in difficult situations, and it will be through controlling your feelings or internal conflict, Such as, the greed and false hope.
leaving a gamble is not so easy, the easy thing is to rest or pause for a moment. You have to control yourself very well if you want to leave the gamble forever, if it just stops for a day or two, it's not a difficult thing to do. Gambling should be in control, not you controlled by gambling.