Best thing you can do in this situation is tell your dd how much you love her , and appreciate having her around . Make her feel safe secure and above all loved . Do some love-bombing on her if you like.
Give her lots of compliments and encouragement for positive things she does ...point is the more confident and happy she Is the less likely she is to be " easy pray " for such a manipulative bloke .( He is manipulative , or else he would be going for a woman in her 20s not a teenager , I know I married a nightmare just like him ..met him at 17 if my self esteem hadnt been in the gutter I wouldnt have looked at him twice ! )
Do lots of fun stuff with her , lots of girlie days and encourage her to bring her friends around to your house a lot .
If she's not got that many friends , try and take her to places where she will meet lots and lots of nice teens her own age ( so she can make more friends ) .
The worst thing you can do is slag off this guy , all it will do is make her think of him in a " forbidden fruit " kind of way which will make him seem more exciting and thrilling .
Re : the aids ...I think he sounds more like a drug user tbh .
I know someone who is HIV + and he's completely healthy looking , clear skin ,really good looking . The virus is well controlled now using advanced drugs , it's not like it was back in the 80s where it progressed quickly and people looked awful.
I don't know about the money , have you asked her where she got it ? Perhaps she has sold something ?
If you really want to limit the time she spends on the Internet chatting to him disable the modem you have / hide the dongle / only have it on at a certain time , then tell her you can't afford the bills as everything has gotten so expensive with the recession so it has to be timed now ? .or take the cable to work with you ? ( the one that powers the wireless router )
Don't top up her phone for her as much if it's got Internet / smart phone . ( can't afford to rather than you don't want to iykwim ? ) .