14 years with addict

Don’t really know where and how to start. 
Don’t even know what support or advice I need or want. My partner is a gambling addict. I am with him for a 14 years and we have 3 kids. I know about his problems almost from the beginning and I haven’t done anything about it but feels like now is the time. Feels like I don’t have no more strength to deal with his lies, with him stilling my money, with him no giving me money from rent and bills and putting our kids in risk. 
Have enough of crying and pretending everything is ok. 
I don’t think I even have strength to give him support or to fight for this relationship. After every situation I want to believe it was a last time and he is going to change but of course it never does. Each time I told him he need to move out that I have enough but never did anything to set up the boundaries. The thing is he and the kids are my only family here in the UK. Told him few times he has to move out but of course I can’t just tell him to leave where he doesn’t have place to stay. Few days ago found out he still from me agin and I went mad, told him he need to leave the next day and that night he left the house without saying anything and he switch off his phones. In the morning when I realised he isn’t there I was terrified because few times before he said is better for him to disappear, like  he wants to take him life. He came back and of course he started to say things for me to say sorry for him but I feel like he is manipulating me. 
he said he is doing something about his addiction and he went for help but when I ask for proves all he says is “ I am and don’t need to prove you anything” part of me wants to believe him but other part is saying that this isn’t true and that is part of his game. 
Really don’t know what to do. I can’t stay with him anymore but don’t know what to do. 
Any advice ?