Am I required to inform those to whom I lied about my lie to them, knowing that the lie was a denial of my conversation with them in a message, and I have repented to Allah, but I fear that this may be one of their rights and that Allah may not forgive my sin?

The liar must repent to Allah according to its conditions. If informing the person lied to serves a benefit or prevents a harm, then he should inform them, unless a greater harm would result from it. If there is no benefit in doing so, then he should conceal himself with Allah's concealment and seek forgiveness from the one he lied to, if his lie caused harm.