You did what you had to do for you and that isn't always easy. You are at a place where you can do that. How would you feel if you let this go on knowing how you truly felt? That's not even taking BF's feelings into consideration and how it would have hurt him. This is so different from what your husband did and I can't even wrap that comparison around my brain.
In fact to say that "you did what you had to do for you" sounds like such MLC bs that I can't believe I said it. We both know that that was distinctly different in everyway. Your ex had way more to take into consideration besides himself. The problem is that he put on the blinders and kept himself from looking back to see what he was leaving in his wake.
This is your time to decide in what direction that you need to go to have a happy life. Taking somebody along for the ride just to fill a void, in the long run would only affect you and BF. I'm proud of you. You done good!