My oldest son?

He will be 11 soon. I just found out that after talking to his grandmother....that he thinks I was born a liar. It broke my heart to hear that. I am a single daddy and I am doing all I can to provide for my 3 kids. I dont know where he is getting that from...he sees his mother maybe 4 days out of the month and I dont know if she is feeding him this...but I have been nothing but honest and have been busting my behind to make sure that he feels loved and secure...but for some reason he thinks I am this horrible person right now. It really hurts me...its pretty real...the pain it makes me feel I am already going through a hard time with what his crazy mother is doing. To hear this really broke my heart. Is this a normal thing for kids to feel when they are with the responsible parent full time? I cried at work...people think I am like a wimpy dude right now...