someone's heart sinks
US /ˈsʌm.wʌnz hɑːrt sɪŋks/
UK /ˈsʌm.wʌnz hɑːrt sɪŋks/

1.
if someone's heart sinks, they feel disappointed or sad
:
•
When I saw the long queue, my heart sank.
•
Her heart sank when she realized she had lost her passport.
if someone's heart sinks, they feel disappointed or sad