I have created two specific mental health communities, one for positive and/or constructive discussion of mental health and wellness, and one to provide an outlet for people's unpleasant/destructive thoughts (sometimes voicing them will help temporarily quiet them if you are in acute distress).
[Mental Health](https://lemmy.ml/c/mentalhealth) | [Void Screaming](https://lemmy.ml/c/voidscreaming)
They won't cure you, but social support is an integral part of a well rounded mental-health treatment and wellness plan, and you deserve to have access to them in a federated/decentralized and non-monetized space.
Cheers!
With credit unions you usually have to find a local one that takes you on the basis of where you live, work, or worship, or of some other unique category.
On the other hand, I also hear good things about Alliant