Have faith in yourself and the invincibility of the Truth. Conduct yourself boldly, honestly, just doing the right thing at the right time. Very soon, the back-biters will have to eat their words and will face humiliation.
Just ignore them... I guess you would be reacting when they spread rumours hence they are enjoying your reaction on it... I think you should ignore them and see what happens.....and always remember one thing "never explain your self your friends don't need it and your enemies won't believe it"