I think how your feeling is very common.. Time will in fact help ease the heartbreak. Very hard to see that now of course.

I think back to my first husband that cheated on me... He just cheated, Something that I honestly would never have thought he would do , Nor his family and mine.. but he did . and he married the woman.. All they do is fight.

Go easy on yourself, what your going through sadly happens to most everyone that is cheated on.

Mourn the man he "use" to, but remember what he has turned into, Not a Man but a POS.. He will likely cheat on "her" Sometimes Karma happens and we get to see it and sometimes it takes forever.