My daughter is 11 and I've explained to her about both my mental health and my physical health. She is a very kind and considerate person, who loves people no matter if the have something wrong or not.
I I'm trying to say, yes your son has gone through some stuff, but he has forgiven you. Sometimes the hardest part of forgiveness is acceptance. You need to accept his forgiveness. It won't come overnight, you didn't 'neglect' him overnight, but it will come. Please be patient with yourself.
Welcome to DWD.