The most offensive is not their lying - one can always forgive lying - lying is a delightful thing, for it leads to truth - what is offensive is that they lie and worship their own lying.
Stay and respond and expand and include and allow and forgive and enjoy and evolve and discern and inquire and accept and admit and divulge and open and reach out and speak up, this is utopia.
And if a friend does you wrong, then say: "I forgive you what you have done to me; that you have done it to YOURSELF, however--how could I forgive that!