Discúlpame,
fue
mi
culpa.
Lo
siento
mucho.
dees-COOL-pah-meh, fweh mee COOL-pah. loh SYEHN-toh MOO-choh
Excuse me, it was my fault. I'm very sorry.
"Discúlpame" is more personal than "disculpe" — use the -me form when apologizing directly to someone you know.