Myusernam it's totally understandable that you are worried and concerned. Lots of parents are. I am some of the time and I've not got your history in my family.
However, I would focus on how you can empower your daughters, as people have described above, to make them aware and to continue to create an environment in your home where they can tell you about anything that is not appropriate.
I have a book called 'The Gift of Fear.' and I think feeling fearful (in appropriate situations) can keep you safe. I never take risks with anyone (now). When I was younger I did take silly risks, accepting a motorbike ride instead of taking a taxi etc. Luckily, for me, all was well. but it was New Year's Eve and at the very least my anonymous motorcycle driver could have been driving pissed!
So I think it's good to be cautious and careful but also not to be controlled by irrational fears.
I certainly was controlled by irrational fears in my thirties and I had CBT for this. It was hugely helpful.
Anyway, don't beat yourself up but do get help if you think you need it. Some of us are just more anxious than others and it's finding the balance between being irrationally fearful and just being sensible and cautious.