Need to vent, I was an asshole

I'm ignoring my ex as best as I can since we work together. A few days ago we were working together as well as with another colleague. I didn't talk to her if I didn't have to and just worked without worrying about her. At some point she stood up and got a bout of dizziness, she sat on the ground for a minute and our other colleague got her some sugar. She was fine after a minute or so, she remainef conscious and coherent while she sat on the ground. I didn't react, and didn't help since our other colleague was closer and already helping, I would have had to walk over her to go get her sugar. Got chewed up for not doing anything later on.

I know I acted poorly by not doing anything, and I feel like shit about it. Sent her a text apologising for it, saying I know I acted like a total dick.

Normally I would have reacted to seeing that. Idk why I didn't here. I hate it. I acted like an asshole.