It is the old chicken and egg question – what came first, the addiction to gamble or the depression. What I do know is that many CGs become depressed as a result of their addiction.
It is good that your bf is acknowledging he has a problem with gambling – I hope by now he has successfully self-banned from the casinos he had been visiting. Words are easy but actions are imperative if he is to control his addiction.
In my opinion he would be better telling his friends he has a problem. Your bf has a recognised addiction that he neither asked for nor wanted so there is no shame to be had; especially now he is determining to fight it. Encouraging a CG to go to the casino, or giving a CG money, is the same as giving a drink to an alcoholic but his friends will not appreciate this if they are kept in the dark.
The best advice I can give you is that you do not enable his addiction by clearing any debts he may have incurred or giving him any money. Looking after ‘you’ is so important because when he takes his leap of faith into recovery the more wreckage there is from his addiction the harder it will be for him to face his demons.
I hope you will post again and tell us how you are progressing but in the meantime, I wish you well.