What Am I To Do??!!!!!! :(((

I have a friend, who by the way is due to give birth any day, her partner is a user.
He used to ( and personally believe still does) inject. hes now on subutex? I think thats what its called, but now shes finding things around like burnt spoons, needles in his car, hes behaving oddly( cleaning maticulously, falling asleep, no interest in anything etc) and im beginning to be a bit worried that hes back on the stuff. My friend has already been through so much with him, and loves him dearly, but she clearly cant continue like this, if hes back using again it would destroy her, shes only 22!
I want to tell her to leave him for her sakes and her unborn babies' but its really not for me to make that decision, in fact if she knew i was on here asking peoples advice shed be upset with me...
has anyone else been in this postion, either as the user, friend or the partner of someone whos using? I don't even know if his behaviour is any indication that he is back on it again, it just seems odd, and i think she thinks he is too.
HELP!!!!
Would love to give positive advice, but from all you've written..seems like the problems still there! God help the baby..hope he/she doesn't have a dependency! It's always the innocents that get hurt! keep in touch! Thanks for being such a loyal friend to them both!
thanks so much for getting back to me! I really don't know what to think or do. can the baby develop an addiction if the mother has never used? surely not? I know the mother has been tested for HIV, shes clear so thats one thing, but i really want her to get away from this man as its draining her of everything and the only person that can help him is himself. he dosnt seem to really want help ( i may be wrong you dont know what goes on behind closed doors and i can only go of what she tells me anyway) but all i know is that she looks so drained every time i see her it breaks my heart!
If what you say is true then he is back on it.