There is always someone.
No one can tell you how to handle the situation because it is never actually the same as someone else's encounter.
And, the problem person is usually a Christian.
We've been taught Grace, and that is usually the first application of affirmatively dealing with it. We've been taught forgiveness, and that is something that happens in prayer.
Often it is someone who has all the answers and yes, sometimes you must follow with damage control.
One thing you must not do is, go to the Lord and tell Him how to handle it. Prayer according to God's Word brings Light - Wisdom. What you crave is knowing what to do when it happens next. He usually doesn't work that way. the majority of the time, the Holy Spirit will give you the words or show you the moves when you need them.
There are times when more drastic measures must be taken. There are times when the person must be confronted. There are times when the person must be told to leave , sometimes put completely out.
Most of us have had moments that were not golden. Here, I am talking about damage to lives, and the quenching of the Holy Spirit in the work of the Lord.
When I was first saved, a wise pastor told me that if I planned to go into Christian service I had to remember two things: first, sometimes the people you have helped the most will hurt you the most; second, the farther you go with the Lord, the fewer there are who want what you want, but the greater the Glory.
Soldier of The Cross, remember there is an enemy who would love to distract you, slow you down and gobble you up, hurting others in the path.
Take it to the Lord over and over if need be. Be careful of creating policies in this area. You never know what He is doing in someone else's heart.
Talk to Him about it today. Be sure it is aloud.