So today my little sister was acting a bit weird. She is 19 years old and lives with me because my mom passed away last year and she isn't stable enough to live on her own. I am doing my best to give her space, stability and support so she can heal. My boyfriend boyfriend I both moved into a place that is a bit to expensive so she is able to have her own room. We made an agreement that she was going to help with some bills, because I just gave birth to a newborn and I'm currently unable to work, but she hasn't really helped much at all. I haven't pressed her about it because when I do mention it she breaks down crying saying she doesn't have it. I feel really bad because I don't want to have ask her for help or cause any emotional stress. I just wish I could take care of her but it's gotten to the point that my boyfriend is in really bad debt because he is taking care of everything. Then not to mention this morning she kinda was being weird. I was in my room feeding my baby but my door was cracked a little bit and I could slightly see if she was checking if I was awake or not like kinda sneaky. It made me feel really uneasy almost like she snuck a boy in the house type of feeling so I hurried to put my baby down to make sure she didn't sneak anyone in the house, but she already left by the time I got up so I wasn't able to see. I ended up checking her computer and went through her texts to see if there was any evidence tbh. However, i ended up finding out she left the house to hang out with a guy she has been talking too. I went through some of their texts and she has been giving him a lot of money like hundreds of dollars when she gets paid. She also has been sleeping with him which is her business, but it's also confusing because she has aboyfriend. It's clear the side dude just uses her for sex and money. I'm honestly really upset because I feel like she is taking advantage of my help and I feel like she is being manipulative tbh. I'm also worried about her emotional and mental health. She isn't making good decisions for herself. I want to talk to her, but I don't know how to start the conversation. Any advice?