After discarding you after you gave it your all, a sweet karma is him seeing you in a different stage of your life and being overcoming with a veil of regret as he starts to realise he let go of the best kind of girl...
Many coming from a breakup often encounter this cliché in many different forms whether verbal or written. It's meant to make you feel better, look ahead positively and realise there's better in store. While this isn't usually false for girls who have been hurt, this type of cliché breakup 'advice'/motivation doesn't really consider the girl lucky that she has actually been let go of by a man who couldn't appreciate what she gave and offered at the time they were together.
I not only think that, 'yes he may actually feel a bit of regret for letting you go', I also think that if he let you go, and you've managed to move onto a better stage of your life and you have someone on the same level, then you haven't lost a thing. That loss was simply a gain.
Why the guilt trap to make him realise he lost something great? It's not about him anymore if he's not yours.
Often people are so damaged they can't see the good that is before them. Often people encounter something far too precious, they can't handle it and they let go of it to drop to something they are much more comfortable with.
The feeling at the start of 'love' is incredible. Often you can't imagine life without them. When hurt, it can be damaging. The way men hurt you and the way they hurt you, shows their character. If the breakup (on his part) was ever so unnecessarily messy, count your lucky stars he let you go, no matter how painful it has been.
Any woman in a better stage in life, wouldn't even consider the thoughts or opinions of the man who hurt her before. What he feels and thinks, is none of our business.