Need advice please!!

[judy]

I agree with Janet about discussing your feelings about how she treats you with your son. You might also want to sit down with her in a quiet place, and with the utmost compassion and tact, try to let her know that she is in a safe place and that she can let down her guard in your home. I wouldn't come out and say it that way, but I would make it my message.

It does sound as if she is having a very rough time, and probably can't be comfortable and enjoy herself freely. I wouldn't take it personally if I were you Mandy. If you can, you might want to try to find some compassion or soft feelings for her. It sounds as if her parents have abandoned her for their own needs. Her Mom is with a 24 year old. That's scary for a 15 year old girl.
She's probably clinging to your son for comfort.

I also wouldn't forbid the relationship - that could backfire. My daughter snuck around with her "forbidden" boyfriend for several years when she was young.
I changed it around, and welcomed him in my home, had him over for dinner, etc. Four months later, she broke up with him!

If she does remain in so much angst after a while, you might drop a lot of hints to your son. Boys are usually very easy to persuade.