I read that as the author, going to the funeral, broke down. That is they felt devastated emotionally, internally and possibly externally as in "broke down crying".

The funeral itself probably continued without any issues. I guess that's another social skills lesson, the world carries on regardless of your emotions.

“Break down” means to cry.

Zwnow threw the undertaker off hell in a cell and he plummeted sixteen feet through an announcer's table.