Called off the wedding

Hi,

Long story so please bear with. Had a partner that I've been with for best part of a decade. 3 kids due to be married. 

Have supported him through many issues stemming from childhood etc. anxiety, bouts of mild depression but for the most part our relationship was good. Last few years have been in slow decline as he has traded one addiction for another. He started to drink more and have frequent mood swings etc, then when that became a problem he switched to impulsive shopping and then gambling. Lottery at first, then onto sports bets, then eventually online slots, which is where things took a dark turn. 

1st time I realised there was a real problem was when he asked to use my phone to download a betting app. He claimed his app wasn't working or something, so I let him. Went to bed and woke in the morning to several transactions in and out of my bank. (from like 11pm -7am) He transferred it back as and when so no money was lost from me but I confronted him as it was over 2k. Also woke to an email about my app being restricted. Long story short he told me he had too much to drink, didn't realise he had spent so much, would never bet again etc etc. He was very lucky as a historic bet came in shortly after which covered most of his losses, so he told me lesson learnt.

Fast forward less than a year later and we were due to move house. Needed his statements for proof of income and he kept dodging. Then confessed he had been gambling again but 'only recently' and 'not that much' but he just wanted to tell me because it 'looked bad' on his statements. Well long story short he had accumulated and gambled in excess of 70k. And that was only the 3 months I had paperwork for. I was in disbelief. He put our house at risk and me at risk of being investigated for fraud for undeclared income, all sorts of horrors. He had to move out or I would have been complicit. I tried to support from a 'this is a clearly an illness' viewpoint, guided him to therapy, suppressed my own feelings to not make him feel worse or guilty. Was rocky at first but then things really started looking up. Now his good mood makes sense because I just discovered he has been playing lottery again behind my back (GAMStop doesn't cover which he knew and I didn't). When confronted he lied about how much, how many times (over £100 last month alone that I know about). This was the last straw. It really opened my eyes to the fact he is an addict and if I marry him, I am committing myself and my kids to a life of uncertainty, both emotionally and financially. I called it off. It was painful but necessary for my happiness, but more importantly my kids. Not to mention this is the 3rd time he has done this after promising he never would again. 

I know I made the right decision because he says he wants to change but his actions say otherwise. He is on the waiting list for CBT but refuses to consider any gambling specific therapies like GA. He is also in complete denial about the facts. He agrees he has a problem but seems to think if I let him move back in he can guarantee me he will never do it again. He doesn't understand this is a lifelong battle not something you overcome one time. He minimises the hurt he has caused and blames me for ending our relationship too quickly over a 'few lottery tickets'. He gave me all sorts of ridiculous excuses ranging from 'he didn't know lottery was gambling' to 'he didn't think it counted or I would have a problem with it'. 

I don't want to be harsh and would like to continue to support him as someone I cared for and the father of my children. However, I am conscious of not blurring the lines. It is still very fresh (as in a couple of days) and he is focused of winning me back as he thinks I am the answer to all his problems. He has offered me free access to all his accounts but I don't want to live that life. I need him to take responsibility for his own recovery. 

Need some advice on how to navigate this situation going forward. We have kids so frequent contact is necessary but I am trying to set a boundary between being supportive, but not being in a relationship without the label. He has been messaging me constantly begging me to reconsider, but I have responded to what is necessary only and in a very neutral way. He is now getting desperate and sending me flurries of erratic messages ranging from blaming me, accusing me of having someone else, to implying he should just crash his car and end it all and then back to begging. I haven't responded to any of those type of messages so far. 

I want to remain civil for the kids but I feel like this is unhealthy behaviour from him/bordering on emotional blackmail and I don't know whether to call him on it or ignore and keep responding only in respect of the kids until he gets the message. He is not a bad guy deep down just very, very lost.