Dealing with deacons can be interesting, dealing with controling deacons and leaders can be a challenge, but dealing with mentally unstable leaders can be nearly impossible.
Early in my ministry I was "blessed" to work with such an individual. Bro Clyde, I'll call him, grew up in this church, and was a deacon as well as worship leader. Clyde was very insecure. Several months into my ministry, I learned that Bro. Clyde had a stroke and nervous breakdown in the previous year. Any leadership role I exercised (but especially regarding worship) was perceived as a threat to Clyde. When Bro. Clyde felt threatened everyone heard about it, particularly the deacons.
Needless to say, he made it difficult to build a close working relationship with the other deacons. He had known these guys all his life. For months I went along, walking softly lest I upset anyone. It was curious to me, during this period of time God disturbed my sleep routine. I would wake up in the wee hours of the morning thinking how the ministry seemed to be at a stalemate. I thought of all those who were causing it, but mostly Bro. Clyde and the deacons. After several weeks of waking early God impressed upon me to pray for these guys, even Clyde, who was trying to sabotage my ministry. As I began to pray, during those early morning hours, I began to sense God showing me how to love those guys, even those attempting to stab me in the back.
One day, much to my surprise, the chairman of deacons came to me in behalf of the deacons. He said "since you've been here we haven't done anything against you nor have we done very much for you. From now on we are going to support you."
Shortly after that Bro. Clyde began to have serious mental issues and stepped down from his leadership roles in the church. He still attended the church and we had an amicable relationship the remainder of my service in that church.
It's amazing how God responds to prayer!