Have you experiences meeting or having people like this in your circle? Yes, I do.
People are still people. No matter how good you are to them, or how genuine you are, they will always find ways of putting you down and most importantly talking bad about you.
Nobody is perfect, but do not judge people easily by one mistakes they have made. Look at the other 9 good things they have done to you.
People will never stop talking about you — for good or bad. For me, people like this just wanted the alliances. Its entirely up to them. But, if you want to play the game, make sure you are damn good at it.