Whilst the amount of money lost is eye watering and the timing unfortunate..many have suffered even worse. many have gone through serious medical problems or worse after drinking or drugs to numb the pain.
you still sound like you are strong and able to cope. the marriage is more important than any money. business people have lost millions and then made a million the next few years, its not impossible.
things can only get better now i hope. be grateful for the good times you already had, and for the people like your wife and sister that need you.
also your problem is short lived in terms of gambling problems. probably less painfull to blow it all in a year than to slowly trickle it away over the decades