My head is spinning

I am hoping to try to make sense of all this. I met my boyfriend 3 years ago after I went through a very messy divorce. At the beginning of our relationship he came over one day in tears and said that he couldn’t take me out as he had been into a bookies and spent all of his money, he was in tears and said that he wouldn’t blame me if I didn’t want to see him again. I asked him if he was a gambler and had a problem, he denied it and said he didn’t know why he did it. I didn’t know any signs or symptoms of gambling at that point. When I had to sell my old marital home I had some equity from the property and he asked to borrow some money from me for bills etc as it was quite close to xmas which I did, he was out working one night and he called me by accident and in the background I could hear that he was in a book makers. I phoned him back and screamed and shouted at him that it was over and that he disgusted me as he had lied again. He swore blind that he wasn’t in there. Eventually after 3 weeks of him saying that it was all in my head, he admitted that he had been in the bookies. We split up for about 4 months in total. I was getting calls, messages non stop from him all this time and eventually we got back together, he promised he wouldn’t go into these places anymore and it took a while for me to trust him things were very good for a while until last week. I had a knock on my door at 650am. When I answered the door there was a bailiff standing there asking where he was. I was in complete shock, I called him and asked him what was going on, and he said he had no knowledge. He seemed to be taking it all so lightly as if it was an every day thing. He did call them and it turns out it was a utility bill from a previous address. 2 days later I was still very shocked and angry about everything. He came in asking me what my problem was. I said I didn’t trust him and that I thought he was gambling again - at which point he went mad screaming at me that it was all in my head and I had problems. He then said he was leaving, he packed a bag and left just like that! leaving me with my 2 children in utter bewilderment. Since then I have been in discussions with him about the future. He still said he hadn’t been gambling that was until I asked him to do a lie detector and that I would pay for it, and that if he wasn’t gambling then that would be the only way to put my mind at rest, it was at that point that he came clean and explained everything and he is indeed a gambler. It has been a very emotional time for all involved. Since then he has contacted GamCare and had an assessment yesterday, the woman recommended group sessions for him which he has said he is starting next Thursday. He keeps saying that he is going to stop because I am the best thing that has happened to him. He says he knows inside that he will stop because he wants to for us. My head is in such a mess I am crying all the time and it isn’t good for my children to see me like that. Will he change / can he change, should I stay with him. I am petrified that if I let him in again then he will just go back to gambling and my kids will have to go through it all again, they are quite attached to him too. Other then this evil gambling we are so compatible and neither one of us will find another relationship so successful.

Thanks for reading, any advice would be greatly appreciated.