Ignorance of Others

How do you tell a grown person that they have said something ignorant? They have no problem correcting you, or well they think they are correcting you, yet you actually know more about the subject than they do and are actually correct. They think just because they are older than you they are that they are more intelligent but in reality you are an adult yourself and actually feel that they are not as intelligent as they should be.
Two people, I know well and had always thought was well educated, has somehow shifted their thought processes in a desperate need to be right, but they are wrong and it is obvious they are wrong. But because they do not want to be wrong they are distorting reality and the facts to make themselves look right. Unfortunately, in reality, to anyone who bothers to check facts, knows they are just saying things to say them. I feel bad for this person, because they do deserve respect, but I feel that I am slowly loosing respect for them and am afraid others will also if they continue saying such things.
It is hard to loose respect for certain people, especially those you have always thought to be educated and deserving respect, because it shatters your reality when they do things or say things that cause you to loose their respect. For a long time I had been able to have discussions, some heated, but most not so much, with these people. Most of the time, I could understand their point of view on things and see why they could come to a certain way of thinking about things, and vise versa. But now, they are so dead set on being right about something that they are, as of right now wrong about, that they are saying things that are incorrect and ignorant.
I feel even worse for them when they say them in front of others, some impressionable some not, because I can see them loosing that respect in others.
I am speaking of two people in my family that I am trying desperately to understand and forgive so that I don’t lose them but some of the things they are saying are beginning to cause me to loose respect for them and am loosing the want to be around them. My fiancé keeps telling to not dwell on it but I am finding that difficult to do.

Talisman