It seems that some people, no matter the circumstances, can't help but manipulate. Everyone has done it, but there is a point where manipulation becomes dangerous and unhealthy. Depending on the source, it can be hard to stay away from these manipulative people and situations, but with perseverance it's possible to stay sane.
To stay sane in the midst of manipulative people and situations can be very hard, especially because these folks tend to be family, friends, lovers, children, and co-workers. Identify these people. Awareness is key.
Sometimes manipulation is very overt or obvious, such as a co-worker or boss threatening you with job loss or more work, or a partner trying to make you feel guilty so he or she can get a desired result. However, it can very often be subtle manipulation, so much so that you might not recognize it. This is called crazy making. Once you can identify what the other person does to try to create chaos, you can become prepared to fight it, which will enable you to remain sane and calm.
Pay attention to your boundaries as manipulators will push them. It is essential to have the ability to communicate clear boundaries. A good indicator that boundaries have been crossed is if you feel angry or guilty. Often when we are manipulated, we feel powerless, so it's important to find a way to take your power back. There are many ways to assert yourself and define your boundaries to the other person. How you respond depends on what you want as an end result. It might be necessary to confront the manipulative person, cut communication off completely, say nothing, put down or enforce a boundary, or talk with a friend and process emotions. Your goal is to stay sane and not react.
Manipulative people come in many forms. A very important thing is to have a strong sense of the type of people you want in your life. Although it does not make the feeling of being manipulated feel any less hurtful, the clearer you are about what you want and what is acceptable behavior will make it easier to identify situations where manipulation is happening. When you are aware of these manipulative situations it becomes easier to know something needs to be done in order to maintain sanity.
Keep on trucking. It takes years to hone these skills. Learn from the times it has happened and take note of what you can do to change.