Your uncle sounds invaluable, I’m so pleased he is there for you.
Tough love is exactly what it says but the word love is important.
Whatever the outcome Melanie, you are not responsible for your ex’s actions.
A compulsive gambler can never walk away from a gamble until all is lost and sometimes only the pain that comes with that loss is enough to cause the gambler to face his demons. Sadly those who love gamblers often have to allow their loved one to feel that pain. Many unwittingly enable hoping to mitigate the almost inevitable pain and in doing so help to keep the addiction alive. In doing so they are not responsible for the addiction or the pain, that responsibility lies only with the gambler. Only he can seek true recovery.
If your ex is still attending GA and trying to work the 12 steps, I am sure there will be people in his group who are aware of his progress, so he is not alone.
I don’t know what to say about the dog. The dog (as I am sure you agree) is the one creature he can be honest with, the one creature who will not and cannot enable him but can give him love however, if the dog is looking malnourished or neglected, then I think it is right to take him back.
Cutting lose can and often does cause spirals of poor behaviour but hanging on, when the addict is not seriously seeking true recovery, will almost certainly be dangling the offer of future enablement. There is no point in making ultimatums to a gambler, who is a master of threats, unless you know 100% that you are willing to carry them through.
I am still confused about the part the girl plays in all your concerns. Your ex has not made the right noises regarding her and although he might just be seeking enablement elsewhere, I think you must be aware that I can have no idea what is actually going on.
I will leave this reply here for now, but please keep posting.
I repeat what I said at the beginning, whatever the outcome, you are not responsible for your ex’s behaviour, nothing you could have done or said would have prevented his addiction, you cannot stop him gambling, you can only point him towards good support and you have done that.