Its one of those situations where its hard to recommend a course of action, because of the possible risk in someone who is mentally unstable, and the difficulty of supporting anyone youve pointed to such an experience online.
Having said that, from SWIM's experience, Salvia has acted as a potent and long lasting anti depressant. SWIM would credit Salvia with kicking him out of a 20 year rut of moderate-mild depression with associated anxiety.
Traditionally Salvia has specifically been used for healing, and divination. Its not a recreational experience , its far too confrontational and bizarre. At high doses it can be like being thrown into a woodchipper. If you want to see what you really are, what you are a part of, what your responsibilities are, and what you are doing wrong, Salvia will show you these things in a blunt and often frighteningly literal way. It has none of the euphoria of tryptamines, and is often completely emotionally flat, as it spells out your sins and shows you possible alternate versions of this reality.
There is a real risk of existential vertigo for the initiate, but on the other hand, this existential shifting seem to be part of the plants power to cure.
If you try it, don't start with extracts. use plain leaf, or chew the leaves, upping the dose until you get effects. theres plenty of info online about methods.
You really have to take responsibility for your own health, and for your own actions. that in itself will be the first step on the path to being healthy and whole.