Although you knew he was disappointed by your extramarital sex activities, you foolishly sent your friend a dick pic & claimed it was sent in error. Thus you presented yourself as a messy person who literally can't keep his affairs in order - someone he won't be having sex with and to be wary of. You should have been direct with regard to the question of jerking off together. For many that activity is personal and private. A simple "Yes" or "No" answer was all you needed. Ask the question and get your answer Blake.