My husband’s old Le’Sabre balked last week when he tried to start it in the extreme cold.

And because my “love language” tends to be sacrifice, I voluntarily hopped on public transportation so he could use my car.

Actually, if I didn’t have to drive every day I wouldn’t. With the bus tracker system, I time my departures from both home and office so I don’t have to wait too long in the cold.

But something happened last Wednesday that put a damper on this new love affair. It was after work. I got on the CTA Brown Line train and took a seat by the door, facing forward. I immediately noticed that a young man in the rear was holding open the door between train cars.

I looked.

The man appeared to be about 30-something. He sat down in a cubicle, but was fidgeting noisily.

I kept looking at the rear door.

Suddenly the man hopped up and stomped toward me, his eyes blazing with anger.

“Why are you looking at me,” he yelled standing a short distance from me.

“What?” I said, shocked that he had gotten out of his seat.

“You’re looking at me,” he said, lurching closer.

“What makes you think I’m looking at you?” I asked, suddenly feeling intimidated.

“I’m telling you don’t be looking at me,” the man said loudly, leaning closer.

At that point, I got up. After all, they were my eyes and I have every right to use them.

“Yeah, get off the train at the next stop,” he yelled. But I wasn’t getting off. I had already spotted the emergency button (it’s located by the exit doors and is outlined in red). I moved quickly past the man and summoned help.

The young man retreated back to his seat. He grabbed a pizza box and bottle of soda and exited through the door between the train cars.

Within minutes, the train conductor responded by stopping the train and coming back to the “L” car. The conductor told me my antagonist was now in his car, and asked if I were O.K. I caught a glimpse of the white wool cap the man was wearing on the platform at the next stop.

After the train started moving again, I looked around.

There were about a half-dozen other people in the “L” car. They were all staring at smart phones.

While I was dealing with a real-time threat, my fellow commuters were engrossed in text messages, streaming and tweets.

If something really bad had taken place, I doubt if any of them could have given the police a decent description of the perpetrator.

While I didn’t expect anyone to come to my defense, I did expect at least one commuter to look up after the dust settled. No one did.

Frankly, the confrontation shook me up. I didn’t know what was about to happen even though CTA is a lot safer than it was when I was a regular rider.

In 2014, CTA saw a 26 percent drop in serious crimes from 2013, thanks in part to the 23,000 security cameras.

Still, videotape is only good after the fact.

Unfortunately, many of us have gone back to the attitudes we had before Sept. 11. Despite the increased threats from groups like ISIS, we are going about our business as if acts of terrorism can’t happen here.

While we can’t allow the threat of terrorism (or violence for that matter) to interfere with our daily lives, we are indeed our brother’s keeper.

That means we need to do a better job of being watchful.

There’s no way a young man should have been able to verbally harass a senior on the “L” and no one sound an alarm.