I Caught My Coworker Red-Handed on Video—Now I Wish I Hadn’t

I work at a consultancy agency. I’ve been with the company for 10 years and was recently promoted. Right after I got promoted, my work files started vanishing from our shared drive.
A coworker, who had vied for my role, would publicly point it out, saying things like, “Oh! I guess our new boss forgot again!” So I had a plan!
I set up a secret backup system and started to keep track of everything. At last, I caught her with no way to deny it.
I actually caught her on video too. Our remote access tool keeps a record of all user activity. She had been either deleting my files or undoing my edits late at night, once everyone else had signed off.
I brought all the evidence to HR. She initially denied everything… until she was confronted with the proof. Her expression turned ghostly white, and she broke down in tears. That was the end of the road for her.
But this is where things start to get complicated… After HR fired her, I froze as I found out she is a single mom of 5. I had no idea until it was already too late.
Now, the office feels split. Some people think she had it coming, while others believe I should’ve talked to her directly instead of going to HR and “ruining her life.”
A few coworkers have been giving me the cold shoulder, and even a friend at work told me, “I didn’t know you were this heartless. Very disappointing.”
I feel terrible… but she did try to sabotage my career. Does that make me the bad guy?