In order to avoid unhealthy people you must first figure out how to discern what is unhealthy. People all go through times in life when they do not make wise choices, but choosing to make better decisions in your relationships is not only a sign of growth but wisdom. To term an individual unhealthy can range in a variety of ways from the misuse of drugs or alcohol, abusive in nature verbally/physically/or mentally, unstable mentally, stealing, lying, or raging anger, etc... Unhealthy people can take on many forms and it can surface at any time.
Know your weaknesses when it comes to relationships. If you know that you have a soft and tender heart for broken individuals than keep in mind, you will attract those types of people and personalities into your life. Nothing is wrong with being there for hurting people, however, you have to know your weaknesses and be strong as to not allow the vulnerability to strike a cord in your heart that will give you an unnecessary tie to that person. It will become unhealthy to you if you cross the boundary.
You may need to put some distance between you and the unhealthy individuals sometimes. There is nothing wrong with moving to a new area and starting over if you have to get away from unhealthy people or a situation. You have to stay committed to changing your future. You have made up your mind that you do not want to have relationships with unhealthy people who have hurt you and you have to stick to your guns no matter what it takes. These days will be some of the hardest days you will have to live but do it for your own well being. You may need to make some hard choices for example: blocking a phone call or changing your contact information. All of these things you choose to do are difficult and may feel foreign but you have to make a choice in how you live your life and what you want surrounding you!