@Lh1993
You are right. I think I will officially resign myself to a life of being single and celibate. I know it sounds extremely overdramatic compared to situations others are in, but I feel traumatised by all of this to the point I really don’t think I could ever let my guard down to trust someone again. Thanks for your views it’s given me a lot to think about and process. I still feel sick to my stomach and I think will really struggle to sleep again tonight but I know I can get through this I am strong and I am in a position financially to walk away. And I am very fortunate for that at least. I never knew the extent of the drug taking or else of course I wouldn’t have accepted his proposal. I thought it was maybe a now and again thing, not a serious addiction. He knows how seriously he has fucked up and I think it’s starting to sink in for him that it’s something I won’t be able to move past. Even if I could, I asked him would he be prepared emotionally and mentally for what that would mean? It would be extremely hard work and would he be willing to give up the drinking and going out for a partner who no longer trusts him?
No - he wouldn’t be prepared to deal with it, and I’m not either. I am worth so much more and I deserve so much better in this life.
Hi OP, I've been in a similar situation myself and didn't want to reply but feel I have to, having read this.
I completely empathise with how you feel, as I was exactly the same. Stupidly, mine was 'contacting' them for years- each time I'd find another message, he'd swear blind it never went further, I'd give him another chance- I was an absolute mug. His bank account showed frequent huge cash withdrawals coinciding with trips away, or messages, and even with irrefutable evidence he tried to deny (he only ever admitted to one- utter bullshit).
Stupidly I tried to make it work with him, but couldn't bring myself to have sex with him and it inevitably failed.
Even more stupidly, 3 years on, we're giving things another go- would never recommend that in a million years to anyone though!
Honestly, quit while you're ahead- he is lying to you, and even if he hasn't yet gone through with it (which is 100% a lie), it's only a matter of time. Sadly it escalates from just googling, to messaging, to BJs, to full on sex.
It's utterly shite and it breaks my heart to think that other people have to go through what I went through- I found it especially hurtful thinking of how little respect he clearly had for women in difficult circumstances who he chose to 'purchase', when I fell in love with him largely because he seemed so respectful and trustworthy.
It took me a good couple of years before I could even consider dating anyone else, but that's ok- it's healthy to take time to yourself after this and learn to be confident independently.
I still don't feel like I will ever be able to trust a man again, or be in a normal pure relationship, but from what I have heard from others, actually you can find that again later down the line so I live in hope 
Really sorry that it's so shit right now, but I know full well that I would have been much, much better off if I'd given up on him when I first found out, rather than dragging it out and keeping on trying, and I look back with sadness that I didn't have the self respect and determination to do so. It's a slippery slope if you allow it once, because then where do you draw the line? I kept redrawing the line over and over out of sheer desperation and I wouldn't want that for anyone else.