Jamie

Your boyfriend should absolutely not have had to justify his sleeping with a coworker after YOU broke up with him. You do not have some kind of special lien period where he has to stay celibate because you were sick of him and wanted to “take a break” unless you both agreed only a short break was taking place. It is unfair to your boyfriend to have made him feel terrible with your immature behavior, an adult learns how to control the negative energy and emotions they give off when those feelings are unjustified.

As for your comments about sex and confidence since this incident, I would not worry about it anymore. As a guy who has been in his position, the fact that he returned to you after you broke up with him and after he slept with this coworker almost certainly means he either enjoys intimacy with you more, or cares more about your other qualities than he does about sex even if she is somewhat more experienced. If you are still anxious and comparing yourself to her, my only advice would be to add a little extra when you are making love – claw his back if you don’t already etc. a guy is really most satisfied in bed when it at least seems like a woman is so into it she couldn’t possibly think about anything else.

If that’s too long basically you are right to blame yourself, shouldn’t worry about sexual comparison considering he came back to you.