Columbo
Never again
Doesn't matter what age she was cheated on, she knows the emotions that come with it. And her going back to the guy doesn't lessen the quality of her opinion, as you said, she was a teenager and did not know any better. But the blame is not on her for going back or that she was cheated on, it's the fact she can understand how his gf would feel, and having insight to the damage it would have caused to see clawson behave the way they do.
I wonder if she'll tell Lawson any of that?