Remember that you are always in control of how you respond to people. No matter what is being said, keep in mind a response that works for you and allows the conversation to continue, but in a more controlled way.
For example, if someone is yelling at you because you left the center light on in the car and it drained the battery, how would you respond? Would you yell too and say, "It wasn't my fault.....I was being rushed.....I thought I turned the light off." I'm guessing you would be angry too and possibly get emotional. Well, all of that is pretty typical, but does it get you anywhere? NOPE.
How about trying something like this, "Yup, you're right. I made a mistake and left the light on. It was a pretty dumb thing to do and I'm sorry this is causing a problem, so what should we do about it?" "How can I help to fix it?" A response like that will help diffuse the other person's anger, allow you to accept ownership of doing something wrong (we all make mistakes, just admit them) and get you closer to a solution. In the end, the problem gets solved. With defensiveness in the conversation, all we end up with is two hurt individuals who probably don't speak to each other for a while. Which result would you prefer?
What if you are the one who is angry and needs to address someone else? You have control here too. You just have to use it.
Let's say that your friend continues to ask you to pick up the tab for dinner when you go out because, "ugghhh, I forgot my wallet again," and you need that to stop. Option #1 is to internally think that you will show them and you will forget your wallet too and make them figure it out. Option #2 is to prepare during the whole dinner that when the check comes you will tell them that you always pick up the check and that it is their turn and just see what happens. Do you see any good results coming from either of those scenarios? You will cause defensiveness in the other person because all of a sudden, this behavior that has been acceptable in the past, is no longer acceptable, but you blindsided them in the moment. In either scenario, both of you will get angry and probably not do a dinner for a long time. What a shame if the two of you lose this friendship over something so small.
If the friendship is important, think about Option #3. You have set a dinner date with your friend and you know in the back of your head that you will probably be expected to pay...because that's what always happens. Call your friend prior to the date and begin a conversation something like this, "Hi Judy, looking forward to our dinner next weekend. I have so much to tell you. I wanted to discuss now how we will be paying for the meal. I know I have picked up the check the last 3 dinners and I am not in a position to do that this time, what do you think we should do?"
Several good things are happening here. First, you are letting your friend know that what has happened in the past cannot happen this time and you are letting them know ahead of time. Second, you are not telling them what to do "You pay the check this time", but you are asking for what you need. No one can argue with what you need, but they can argue with what you tell them to do. You give the friend the option to be prepared to pay when day arrives or to cancel dinner if they choose not to want to pay. By getting the other person involved in the solution and not confronting them on the spot, you show respect for them and also allow them to take ownership in the solution. Whatever happens with dinner, you decided together. Hopefully that saves the friendship.
This is just the tip of the iceberg with defensiveness, but know that if you can avoid defensiveness in the conversation, you are more likely to move towards a solution and a productive conversation. I look forward to hearing your successes with avoiding defensiveness.