Solution 1:

You can use:

Sob
Weep convulsively

As in slowly stopped crying, so far I have never read about its onomatopoeia.

Solution 2:

Waa! He wants me to cry! Boo Hoo! You're so mean! Sniffle.

Waa

Meaning: Crying

Definition

A whiny term that sounds like someone crying; used jokingly.

Example

"I forgot to get a coffee at Starbucks today. Waa!"

slangit: waa

 

boo·hoo

ˌbo͞oˈho͞o/

exclamation

  1. used to represent the sound of someone crying noisily.

verb

  1. cry noisily.

"she broke down and boohooed"

google: boo hoo define

 

sniffle

snif·fle

ˈsnifəl

verb

  1. sniff slightly or repeatedly, typically because of a cold or fit of crying.

noun

  1. an act of sniffing because of a cold or crying.

"he was restraining his sniffles rather well"

google: sniffle define