ANSWER:

Do not believe what they had said and conveyed to you about others talking behind your back as this is against the instruction of Allah.

Deal with them normally and with good behavior as Allah will hold them accountable for their actions and He will reward you for your patience and tolerance. 

Sheikh if the relatives are talking bad about us behind the back as i got to know from my cousins and they too were involved in that talking with them which they came to me and said sorry for the talkings and the other cousins are sweet with me. How to deal with them when they come and talk to me?