Train yourself to not care what people think by focusing on the most important things in your life. When you realize that you have healthy body, wonderful family, a great job, and loving friends, all the bad things that people are thinking, and even saying, about you are irrelevant.
People will always talk behind your back. You cannot change that so let them do it to their heart’s content. But don’t let those negative things ruin all the good things that you are enjoying right now. Yes, it hurts to hear things that are untrue, but it will hurt you more if you will let them affect your life.