Are you sure that drugs are what caused these problems? It is not clear what causes schizophrenia. There is some genetic factor as well. Anxiety can often be brought about due to traumatic experiences and some people are more naturally inclined to it too. You might have introduced her to drugs, but it was her choice to get involved. I don’t believe your guilt is justified. If you want to help her, just be there for her, encourage her to talk to you and stay clear from drugs.