Vengar means 'to avenge' or 'to get revenge'. It's a powerful and intense verb that you don't often find in love songs, making it a unique word to learn.
In "Tu Boda," the singer is devastated watching his love marry someone else. He sings, "Me iré al infierno, pero me tengo que vengar" (I'll go to hell, but I have to get my revenge), revealing the dark and dramatic turn of this tragic love story.
This song tells a dark and dramatic story of a man attending the wedding of the woman who broke his heart. He feels an empty void and has been obsessing over her, convinced he needs revenge even if it means he'll go to hell: "Me iré al infierno, pero me tengo que vengar" (I'll go to hell, but I have to get my revenge). His plan is shocking and violent. He imagines interrupting the ceremony in front of all one hundred guests to "manchar el vestido blanco de rojo" (stain the white dress red) so they can have one last, eternal dance together, whether in heaven or hell.
But as he walks down the aisle, seeing flashbacks of their past promises, his plan changes. He sees her happy and has a moment of clarity. He realizes he can't destroy her happiness and decides to let her go, saying "Me arrepentí de quitarte tu felicidad" (I regretted taking away your happiness). Instead of a murder-suicide, the story turns into one of tragic self-sacrifice. He says his final goodbye, wishes her luck, and tragically declares, "bendigo mi muerte" (I bless my death).