Let it ride. You need to worry about you. They are HER parents and are going to side with her 99% of the time regardless of the issue.

If asked, tell the truth. Do not lie to shield her from the issues but do not contact the parents. It looks tit for tat or pissy.

Me 44 She 46
S13 D9
M18 T23
3 years DB'ing
Successfully busted