Glen,

I can understand how difficult this situation must be for you.

As in most conflicts Matthew 18 comes to mind.

15"If your brother sins against you,[b] go and show him his fault, just between the two of you. If he listens to you, you have won your brother over. 16But if he will not listen, take one or two others along, so that 'every matter may be established by the testimony of two or three witnesses.'[c] 17If he refuses to listen to them, tell it to the church; and if he refuses to listen even to the church, treat him as you would a pagan or a tax collector.

So the first step is a face to face confrontation with the leader. If that group leader is still not listening confront them with a couple of other people that they respect. Often if it is someone else from the church that they deeply respect the conflict will end in that meeting.

The final step would be to involve church leadership at the highest level. I have had to do this on a few occasions and even go as far as removing the person from leadership and volunteering in every area of the church because their presence was so toxic. After 3 months the person no volunteering and 6 months out of leadership this person was eventually a healthy participant in the church.

But you also specifically ask about prevention. One of the best ways of prevention is to initiate an application process for leadership. We actually use a formal written application and an interview for all group leaders. This helps us discover character issues and disloyalties before we place people in leadership and gives us something to point to later if a problem does arise. When they sign the application form it states that they will submit to church leadership or resign as a leader if needed.

I will be posting the form in our article section soon.

I hope that helps.