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If you want your fiancee treated you must first deal with the crisis. If she is a danger to herself or others she can be escorted to the hospital and evaluated for both issues. The police will take her to the hospital. She will then be evaluated. If she is high that is the time to get her there. She has to be in crisis.
Any treatment outside of the hospital can come in two forms. If you find an addictions program they can address the illicit drugs and the other addictions. They would need to have a psychiatrist that treats those with mental health issues. If you choose a psychiatrist to treat the mental health he or his staff have to have experience with addictions. Treating one or the other won't work. The problem as you said is that she doesn't want to go. Let her know what happens if she doesn't. Try to reason with her first. In the end, you have to decide as a couple how to proceed. and on your part what you will tolerate.
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