It does help to communicate with people who have been in your shoes. Any of us who have lived long enough usually encounter a relationship with someone who we have to disconnect from for our own welfare. I unfortunately got involved with several before I learned to choose differently. I was raised to "help and rescue" the strays, but it got me too involved with people, both men in relationships and women as friends, who would absolutely drain me with their own dysfunctional behavior. I felt obligated to put up with it because they were so needy. Not now. Live and learn.
It's hard to let go, but I think you understand that it is best to let go of unhealthy relationships. Have compassion for them at a distance, but don't let them abuse you by being close to them.