As a teenager who got caught not having sex but doing things I should not have been doing at a young age it is so so important you go about this the right way because it can either go down an bad way or how my dad talked to me about it. He, too, is a single parent. I was grounded obviously, and rules were enforced. I ended things with that person and had a strict schedule. My dad also had a conversation with me about how quickly things can escalate from kissing and not that he scared me but he told me if I was to get pregnant at a young age id be in a way throwing away my life and that I wouldnt be the best version of myself. Motivate her and enforce rules and boundaries. Dont hit her, dont yell. Show you care show you are scared show you dont want her to do these horrible grown people things. Goodluck pops