Can you do stupid things when you're 19, then look back and be ashamed of them?

I'm now 26 and can't imagine ever doing what I did at age 19.

At the time, I got involved in some type of gossiping that nearly destroyed a marriage. I was easily influenced by some older woman in her early 40's. Initially I had issues with that lady at my former workplace in the beginning and others (even that guy we lied about) stood up for me. The lady apologized the next day and our friendship started.

All of the sudden I was under her influence and several months later, she called the guy's wife to inform him about his ''affair''. She told the guy's wife that I confirmed it's true and we got proof; false... we had none. So the next day, our co-worker found out I was behind that too and couldn't believe it. He even said ''and we all stood up for you, I defended you against her and now you do that, don't want to talk to you''. He didn't speak to me for several months. I was too ashamed to apologize every time I had to ran into him at work. I just didn't say anything.

Looking back, yes that was messed up. I don't imagine doing that same thing at this age. Can you really be that stupid at age 19 and years later be ashamed of how you acted?

Updates
11 mo
It was indeed defamation what we did; inventing about someone having an affair. Well she got me involved in this... I was a young girl that got influenced easily at the time.
Can you do stupid things when you're 19, then look back and be ashamed of them?
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