Michael was particularly cruel to Connie in GF and II. In GF, Michael has her husband whacked on the day he stood godfather to their son.
So what? Carlo had to be killed sometime. Michael certainly wasn't as "cruel" to Connie for doing it on that day as Carlo had been to her. After all, Carlo knowingly played a critical role in Sonny's death (that, of course, is why he was killed), in addition to beating Connie repeatedly. And it's not as though Connie would have been dramatically less affected if Michael had chosen a different day to do it.
