Distancing myself from/ditching a old friend?

Talk to him. Ask him if he thinks the relationship is going well. Then tell him that you don't think it is going to work out anymore. That you guys don't have common interests anymore and that you think it would be in both of your interests to end the relationship. If you are feeling embarrassed when hanging out with him then you need to end it. It's hurting you and him. Don't be mean or harsh. Let him off easily. Be kind. He will make new friends and it is not your fault if he doesn't get friends. He has to be responsible for himself and his relationships. Good luck and I'm sorry.