Here's some of my thoughts on the matter. Keep in mind that I have my own problems, so take my thoughts as simply my own and not in any way suggestions you should act on.
It's very common for people to change their mind and backtrack on any "agreements" they had. Emotions are indeed a fickle thing, and sometimes you just don't know how you are going to react until confronted with the reality of the situation. My guess is Hubby for the first time saw you as possibly slipping away from him into another's heart, and this really bothered him (as it does most men). Whether his reactions are reasonable or not is debatable, depending on your values, but it's nonetheless the reality of the situation. He is not of the mind to share you right now, and until he is ready to do so, your actions with Sweetie are going to be viewed as an affair. His demand that you stop with the texting shows that this is his mindset. You refused, so in his mind, you are showing that you are going to continue regardless of his wishes. He's thinking "She doesn't care that this is eating me up inside". Feelings are feelings, no matter how unreasonable they may seem to others.
You say you've been happy only about 1/3 of your 23 year history. That's a long time to be unhappy. Any MC along the way? One thing I'm always leery of is people re-writing marital history. This happens ALL THE TIME when people are in the grip of NRE. Someone shiny and new comes into your life and treats you like a queen, and all of a sudden you discover you've been "unhappy" the majority of your marriage. If you're serious about staying married, I would urge you find a qualified marital counsellor. His belittling and other behaviors are not acceptable, but many couples have used MC to help work on themselves and realize the impact of their words. Sometimes having that third party can cause you to really work on those communication issues.
You say Sweetie doesn't want to be the cause of any marital problems. Well, right now he is. The bottom line is you want a romantic relationship outside your marriage and your husband doesn't want you to. Until your husband changes his mind about that, any relationship you have with Sweetie is going to cause marital strife. If Sweetie were being totally honest with himself, he would realize this and back away from your situation until your hubby gives his blessing. If that blessing never comes, well, then the ball's in your court as to what you want to do.
Again, just my thoughts.
Last edited by learninginTN; 01-28-2013 at 05:42 PM.