Mr. Fu, My Wife Has Become the Head of the Hidden Family.

The heroine was misunderstood for having an affair, was kicked out of the house while she was pregnant, and had to leave the house. Five years later, the male protagonist returns with a genius cute baby. The male protagonist discovers that the child is his, and the female protagonist already has a better suitor. Cute baby assists + chasing his wife in the crematorium + slapping him in the face + reversing his identity