Do you know anyone who’s just liable to pop off in a rage at any given moment?…Someone you just dread being around because she just might snap at you for the least of offenses, or for nothing at all? Sometimes such a person will be fairly polite for an extended period of time, causing you to loosen your guard and open up to her–share some of your opinions–only to have her lash out once more, causing you to retreat again and making you want as little conversation with her as possible.
I’m not an expert in dealing with such a person. But I’m getting more experience and I can think of a few lessons learned in what is, perhaps, not the prettiest way.
First, I hope you don’t allow yourself to become embittered toward such a person. If you do, you lose the best chance to do something that builds patience (James 1: 2ff ) Instead of shouting or “smarting” back, try gently explaining that, while you do not deserve this kind of mistreatment, you refuse to lash out in anger against anyone and that you will do your best to continue to be nothing but kind regardless of how you are treated. Each time you respond in kindness, you’re building spiritual muscle that makes you stronger for the next encounter.
Second, resolve to pity that person. Just be glad you are not her. Be glad you are the recipient of ill treatment rather than the dispenser. Such a person is not very happy. Troublemakers are troubled people. Besides, you have the favor of the Lord if you do not seek to retaliate in such a scenario. Stay on His side. 
Thirdly, Read the last few verses of Romans 12 and think of some practical ways in your specific situation in which to heap coals of fire. In my instance, this person told me exactly what inexpensive item she’s looking for right now on eBay. She told me this just before exploding at me. Well, I can shop on eBay, too, and I may search for some coals. I just may find some (at a bargain price) to heap on her head. Perhaps it would help move her toward heaven.
Fourthly, if you believe there might be a disorder or a chemical imbalance occurring that’s causing outbursts of anger, pray and consider toward finding someone who might be able to convince the angry sister (or brother) to seek medical or professional help for the problem. Often this is very difficult to accomplish (because everyone’s afraid to get close enough to the ticking time bomb to suggest it), but I have seen angry people modify or eliminate the problem with proper help. They’ve gone on to live happy and productive lives. Homes have been stabilized and marriages strengthened by medical intervention. It’s just a fact.
Fifthly, don’t put too much stock in a criticism if it is from lips that alternately yell and scowl and bear gnashing teeth. Go to an older, wiser, unbiased person and ask for an assessment before you enter the world of guilt. Most importantly, go to the Word.
Lastly, remember the lamb that was led to the slaughter, opening not his mouth (Is. 53:7 ). Remember he spoke from the cross saying “Father, forgive them, for they know not what they do” and made that forgiveness possible beginning at the following Pentecost (Acts 2:37,38). Remember your own state without that lamb’s sacrifice. (Your sin might not be unrighteous anger, but it is something!) Be sure that you are on-the-ready to forgive if penitence is achieved in the life of the angry sister. In fact, you should be in prayer for that penitence.
Remember, the golden rule was meant for golden opportunities. When someone pops off at you, it’s a large and spontaneous and, yes, a golden opportunity to exhibit your faith in the command of Matthew 7:12.
