Thanks @redgreenred for your message.
I can totally understand the dilemma that you're in and I know how hard it can be. There are a couple of things at play here which are really important for you to be aware of - if you aren't already.
As far as men are concerned, their primary objective in a relationship is to make his woman happy (contrary to public opinion). Nothing makes him feel better. On the opposite end of the spectrum, when he can't do that, he feels like a complete failure. In fact, it's even worse than that. It's as if he's not worthy or good enough. Most guys aren't sure how to make their woman happy, which is why they end up finding ways to distract themselves ie absorb themselves in work etc
Now from your perspective - correct me if i'm wrong, but I suspect part of your intention of telling your DH about the other guy was to get him to 'step up' and make more of an effort and create more passion and closeness in the marriage?
Unfortunately most guys fail to 'pass' this test. Why? Because rejection plays such a massive part in a mans ego and when you built a connection with the other guy, this would make him feel like he failed at the deepest level.
The truth is that, if you were to stay in the marriage as it is now - in the 'workable marriage' that you described it as - it will never make you fulfilled and in the long run, you will both suffer.
The main question I have for you is this - have you truly given everything you possibly can to create a passionate, loving marriage? If you genuinely feel you have, then ending the marriage might have to be an option.
However, most individuals fail to truly make a commitment to meet their partners needs - not how you think they want it but how they actually need it. Yes, this requires the other person to play ball as well but if you are meeting their needs, it's only natural that they will reciprocate or make a commitment to do so.
So before making any big decisions, you need to answer this question. Then and only then can you potentially explore leaving the relationship.
Hope that all makes sense.
Thanks