Dear Rabbi, I have a close relative who all the time speaks lashon harah to me about people from the community. When I want to stop him from speaking (in a gently manner) he gets angry and tells me that I am not on his side etc. ? So i am really in a dilemma, from one side I want to help this person and listen him in order to give emotional support, but on the other hand it is prohibited to hear lashon harah and i have also a mitzva of tochacha. What should I do in this case ?

Although listening to, and especially accepting lashon hara is a very serious offense, if you cannot get a person to desist from l"h, but you are sure that person needs your support, it may be better to remain silent. However this is an issue that requires clearer understanding of the situation than your brief question offers. Here are some questions you might think about: Is the lashon hara having a bad effect on me? Is it making me less sensitive? Do I believe any of it? Will I be able, in the future to minimize the l"h? Is my relative in need of emotional support by problems of his/her own making. Does he/she need counseling or therapy? Am I able to mitigate some of the bad feeling indicated by lashon hara? Try to talk these issues over with a Rabbi. Try to learn more about l"h and develop more sensitivity, while trying at the same time to give support. Sound impossible? It may be, and that also requires watchfullness.