Loves2Walk - I read your post really carefully and yes, there has been a real turning point.
If an affair (emotional or physical) is ongoing however, what you might find is that this new phase between you doesn't last, but it will be different nevertheless to how it was before you talked.
I've said before - if not on your post, then on these boards - that I had a similar chat with DH 6 weeks before discovery. My main focus during that chat (which I started) was how his changed behaviour was affecting me and the DCs, but I remember so clearly it started with me saying that I felt he just wasn't "into me" at the moment, and I wondered why?
I didn't have anything like the insight I do now about affair behaviour - and all I had to go on was gut instinct about an affair, the first such inkling I'd had in 24 years. In retrospect, I don't think I really believed it was possible, but this nagging instinct wouldn't go away - and I was such a non-jealous, suspicious person. Of course my DH denied that there was someone else and even made a joke about how implausible that was - and he reacted rather like your H did the other night.
He admitted the behaviour I'd noticed - and we had a long chat about the stress he was having at work. So much of what he said about this work stuff was truthful and because we'd always been such a close couple, I was able to identify with the situations he described and the people involved. He agreed to seek help from our GP if things didn't improve. He was in tears about how he'd made me feel - and told me he didn't just love me, he adored me - that I was the love of his life.
After what had seemed like a breakthrough, his behaviour towards me did change. He stopped creating arguments with me, but his behaviour towards the DCs didn't improve dramatically - and he started to have arguments with other people, which was so unusual.
In retrospect, over the next 6 weeks or so he started the process of coming back to me. I started to see glimpses of the old him, but there were still uncharacteristic (for him) episodes of insensitivity towards me - and we had a much briefer but tearful showdown a week before discovery, when he had been particularly unsupportive about a business setback of mine. However, this time he realised how inadequate he had been and even bought me a really thoughtful present to cheer me up after this setback.
We've often reviewed what was actually happening during this phase and he has told me that the night we had that first chat, he felt terrified. He hadn't realised how bad he was at compartmentalising and had believed that this affair, which had no future, would burn out quickly with no collateral damage. His instincts were to deny and reassure - and he says how much he actually valued the opportunity to be honest about the work stress, because that at least was true. Tellingly, he says that he could not have met or communicated with OW that night - I was being so loving and supportive, it would have felt awful.
He says that over the next few weeks, he started to see the OW in a much clearer light, but his attempts to extricate himself from the relationship were causing her to become more volatile than ever - and so the stress got worse for a while. He started to worry that there would be some fall-out from this after all, as she became alternately adoring and hysterically angry with him. He is able to pinpoint various occasions/moments - that I also remember very well - when his deep feelings for me came flooding to the surface.
Ironically, on the very night when I made my accidental discovery, he had refused repeated requests from her to meet up after work. He says that having tried to end this twice already, only to relent quickly afterwards, this was the first time he felt absolutely resolute that he could stick to his guns and end the relationship. He felt a spring in his step on the journey home - and phoned me to see if I was still up. He recalls feeling overjoyed that I was, although wondered why I sounded a bit strange. Unbeknowns to him, half an hour earlier I had found a lost phone with incrimating text messages on it - and I was in shock.
So what you might find is that your talk has re-focused him on what he might stand to lose. But if there is a relationship with this woman - and in your case he is seeing her every day - you might see him behaving better towards you, but worse to others. If he's been physically unfaithful, he might start to feel proper guilt for the first time about now - and so your intimacy might still not be as good as it once was. It never is while there are secrets.
If there is an affair, the next catalyst could be you finding out, him ending it with her, or him increasing his involvement with her. It so depends whether he has been addicted to her as a person, or addicted to the feelings the affair has given him. If it's the latter, your talk will have hastened the affair's end. And given what you've written today, I think that's most likely FWIW.
I do think however you need to know if an affair has happened, because I suspect you will always wonder and your trust will be compromised, without a chance to regain it properly. So in your shoes I would continue to check things (the E mails especially) and I would also try to get a look at those Blackberry invoices however I managed it, by fair means or foul. I wouldn't want a life of wondering if something had happened - and trust me Loves, without disclosure or discovery, your marriage will never reach its true potential.
My H and I have often speculated what might have happened if I hadn't found out that night. The affair would have ended, of that I have no doubt, but it could have become what I call a "gateway" infidelity. My H would never have had to face up to the hurt and pain of it all and once you've been unfaithful and undiscovered, it's easier the next time.
For a long time, my H believed that the whole thing was so stressful - and he felt so horrible much of the time, those memories would have deterred him. But we have now accepted that there comes a point when those bad memories might have faded - and the ones about the excitement would have remained more vivid. Discovery was the best thing that could have happened in our circumstances.
My H at the time would never, ever have disclosed what he'd done. So we would have resumed what had always been a happy marriage - but one that needed revitalising after 24 years - with this cancerous secret between us. And it might have happened again - and this time possibly with more devastating consequences. We genuinely shudder to think what a lost opportunity that would have been.
I'm saying all this so that you don't fear discovery and to stop the temptation that you might be feeling, to put your head in the sand. It might just be the best thing that ever happened to your marriage.