If I were in your position, here's what I would do:
1. I would tell my daughter's friend's mother that it is inappropriate to be nosing into my daughter's private life.
2. I would check in with myself about my entitlement issues and stop snooping in my daughter's things.
3. I would check in with my daughter about safe sex issues and see if she needs help finding birth control, barrier methods or more information about sex.
4. I would look into getting a hobby to help me redirect my free time now that my child has reached the age of adulthood and I am obviously having a hard time letting her go.
I hope this advice is helpful.