I was a young teenager with depression and had a psychotic break. It was probably the hardest point in my life (I'm now a 36 year old father). Your child sounds like they might be having an extremely hard time computing all the changes they're going though, and possibly having identity issues. It's gotta be hard.
It sounds like you're doing the best you can, I wouldn't be too hard on yourself. One thing my dad did for me when I was younger was tell me if I ever needed anything, if I ever needed an exit because there was stress I couldn't talk about he was there and there would be no questions asked.
If you can't get a word in, maybe write them a letter and let them know how you feel. Let them know that you're concerned, but if they need space then don't worry, just let them know you're there for them. They must be going through something and if they need anything - you're there for them. They are just becoming an adult, I wouldn't dismiss them as becoming like their birth mother or as someone you cannot see eye to eye with, that would drive a wedge between you. They are figuring out who they are and what being an adult is. Life is really hard, and for some people it begins to be hard as soon as our adolescence begins.
If it's black mold soak it in a very light bleach mixture (2 teaspoons for a gallon of water) for an extended time. Like 24 hours, and keep it submerged. Afterwards clean it thoroughly with water, if that doesn't get the mold out I would replace it.