Dear Denise
It is high time that you were put back together again.   Just as the only person who could change your husband is your husband, so the only person who can give you back your self-esteem and confidence is you – and you will.
Heartfelt letters to active CGs I’m afraid have little or no impact. Due to your husband’s addiction his self-confidence and self-esteem will be nil and so he will not read the words as you have written them. His addiction ensures he lives with failure and disappointment, he feel worthless so why would you love him. 
I cannot tell you what to do, I cannot judge – I know that there are many different outcomes for those who live with this addiction and separation and divorce are far from unknown and often the only way forward.  
It is likely that there was fairly continuous gambling after your husband stopped going to GA – the addiction has nothing to do with money but everything to do with the mind of the CG.   If your husband’s addiction was filling his mind there would have been no room for honesty and truth.
His mother’s enablement in February will have fed his addiction and the chances are she will never see that money again but that is her problem, not yours. You warned her and you could no more.   Her denial of her son’s addiction would only have hurt her son and that is a sad indictment indeed. 
I have no problem understanding that from the outside everything looks great because secrecy is important to the addiction and it is divisive in families. I hope you find support in your friends and family – you deserve it.   I think it is best to tell people that your husband is a CG because there is no shame in it – he neither asked for, nor wanted the addiction.   Most of us agree that only those who have lived with the addiction understand what it is like to live with it and so I believe it is best to make a statement about it and not ask for opinions which are seldom helpful.
I am sorry I was not the first person to see your post because I have to be the one to tell you that Gambling Therapy is not funded to support in the UK.   You will have found your post difficult to write I know but I am re-directing you and not rejecting you.   Please copy and paste your post in gamcare.co.uk who will support you as we cannot.  
I lived with the addiction to gamble for 25 years but now I am fully recovered so I hope that will give you hope. I have taken the experience and used it to help me in my life rather than allowing it to keep me as the pathetic victim I had become.  
You can rebuild your life, you can give your sons a parent they can trust and lean on.   You can be the person you want to be. If it wasn’t so I wouldn’t be writing to you now.
I wish you a wonderful life Denise. The greatest revenge you can have on the addiction to gamble is for you to be happy. 
Please use gamcare – they are there for you and for all those in the UK.  In the UK we are funded only for friends and family of CGs and CGs who have been through the Gordon House rehab programme.
I hope it helps you to know you are not alone. I hope it helps to know that those of us who come out of the shadow of the addiction to gamble live healthy happy lives. Self-respect and peace are within ‘your’ grasp – you are retaking control of your life. Well done.
I wish you well