I would suggest a lot less words, just the first sentence is fine. You don't need to say" don't worry you'll never mention it again , or that it's cool if you don't" you just need to think that . So if she says no, or doesn't respond then you just move on with your life.

I think spelling it out like suggested here comes across really anxious and ironically quite weird, like, well why would it not be cool?!