As Calvin said "precise" is unnecessary and/or not a good word to use here. There are other adjectives you perhaps meant to use?
- Comprehensive - explained it really well.
- Thorough - explained it really well.
- Thoughtful - considerate and well thought out.
- Helpful - it really helped me.
Otherwise it is fine:
Had it not been for your helpful response, I would have continued using that idiom without knowing about / realising / understanding the sexual connotations!
It is slightly formal, as Kayla said, but not an unusual way of writing. I would write like this if I was being polite to someone I didn't know.
You could also say:
- Thanks for letting me know about that idiom. I didn't realise it meant that!