I have several friends like this. I may occasionally do this, too. Thinking about any issue over and over again may indicate what my therapist calls rumination which may indicate some OCD is involved–Obsessive Compulsive Disorder. OCD often goes occurs with ADHD and depression and or anxiety. The rumination keeps you thinking in loops over and over and having a hard time stopping. I think writing down your thoughts and feelings about a situation may help you to analyze your feelings and help you to figure out how to handle a situation. Impulsivity of ADHD in saying things that may offend other people may be involved, too. Try to distract yourself if you think you are going to say things that may offend someone until you can think through what you want to say and make sure what you are going to say is accurate and not going to offend your friends. I hope I do not offend you here, but rather offer you some insight to what may be going on.