This wasn't my experience at all. I was hurt and pissed and hurt and pissed and made sure EVERYONE knew it. I talked about it (in appropriate ways with appropriate amounts of information depending upon to whom I was speaking) with every person I came in contact with. Store clerks, friends, family, my hairdresser, colleagues. Of course with colleagues I had an ulterior motive b/c since xpiece of shit works for the same agency I do, I wanted to make sure people knew he was a dirtbag. But on the whole, sharing my feelings helped me process them.
But of course your viewpoint is acceptable too. It sounds a little like you don't have an issue with the D itself (b/c if he's going to be an asshat then D is an acceptable route for you) but more your feelings of disappointment lie in that he turned out not to be the good person you spent years thinking he was.
Perhaps people are reacting to the lack of display of strong emotions on your part about anything? Your post here does feel rather sanguine & well, that's the way the cookie crumbles. Perhaps if your IRL friends never saw you really upset then they are assuming that you weren't/aren't and that would seem a bit odd. But then, if they aren't close enough to you for you to comfortably share how you really feel with them, who the f*ck cares what they think? As long as you feel you dealt with the bad feelings and now feel optimistic and happy to keep moving forward, that surely is all that counts.