Only those who have disciplined themselves to be self-controlled and honorable can be trusted not to talk behind your back; with others, you should expect it.
When this happens to you, and it will happen to you, don't worry about it. They are talking about you behind your back because they are behind you.
They are jealous of where you are,
and either want to be you or want to bring you down to their level,
which is much, much lower than you want to be, I can assure you.
People like this give no thought to honor or to what's right; they simply take pleasure in malice and have nothing better to do with their small lives.