嬉し泣き

うれしなき【嬉し泣き】

～する weep with [for] joy; be so happy that one cries; cry [shed, weep] tears of (pure) joy; be overcome with tears of joy [happiness].

●ほっとしてうれし泣きする weep joyful tears of relief

・当選が決まって, 後援者たちはうれし泣きした. As his election became certain, his supporters wept for joy.

●うれし泣きに泣く ＝～する.