Mod Sun’s opening up about his split from Avril Lavigne … saying it was brutal to move on, especially when he had to replay the heartbreak every night on stage singing their song together.

The singer told Bunnie XO on the “Dumb Blonde” podcast it just so happens his biggest hit, “Flames,” is the one with Avril … but since it’s his song, he wasn’t about to rob himself (or fans) of performing it live on tour.

Mod went on to say it was tough to play — and even harder to hear — but he pushed through. Performing it night after night was difficult, yet getting emotionally wrecked on stage in front of people ended up being the thing that healed him.

Remember, Mod and Avril had that whirlwind romance back in 2023 — they even got engaged! But she called it quits and popped up with Tyga that March … a move Mod says totally blindsided him.