I support online groups, however I'd prefer staying anonymous which simply isn't possible without faking your account on FB.
Reddit provides similar functionality and let's you stay anon. There's subreddits for pretty much any situation: alcohol abuse, drug abuse, kids growing up with narcissistic parents, spouses living in sexless relationships, etc etc. I did some research into the topic after reading this: https://www.washingtonpost.com/news/the-intersect/wp/2016/01...
Just Google your specific situation and Reddit will probably have a support sub.