He Was Mad at Me.

Yesterday, I made one of my colleagues angry because of an insensitive action.

What you wrote is ok but there is something about the last part that is not smooth.

However his anger was only increasing.

I had become the focus for his accumulated frustration about another big problem from the depth of his mind.

Yesterday, I made one of my colleagues angry with my insensitive/thoughtless behaviour/remarks.

However his anger was just increasing// getting more and more extreme/intense

I provoked the release of his accumulated frustration about another big problem from the depths of his mind.

I was not involved with the other problem directly.

I noticed/realized that he was frustrated by the other (big) problem more than I had expected/realized.

However his angry was getting worse.

Yesterday, I did something insensitive that made one of my colleagues angry.

I apologized, but it only made him angrier.

He was frustrated about something else, and I provoked him to take his frustration out on me.

Schoenewaelder’s correction is great. Personally, I think “the depths of his mind” sounds poetic, so I would leave it out.

I wasn’t directly involved with the other problem.

I didn’t realize that it frustrated him so much.