What makes a home wrecker?

I 42F and not dating this guy but were fwb (41M). He was in a relationship back in June but said he couldn’t see a future with her and they dated for 6 months. I slept with him with the knowledge that it was over between them. Turns out he was still in a relationship with her but it ended shortly after I slept with him. This evening my kid called me a home wrecker because of it. I’d like honest feedback on this. Once I found out I handed him his ass and cut contact. He has since messaged me saying he is no longer in a relationship and wants to know me better but I have no interest.

TDRL: cheating