I am glad you found the courage to speak up about your girlfriend and your anxiety. It sounds like there are a few things going on that have to do with your relationships with people and having difficulty making, expanding, limiting or keeping connections. I would suggest that since it is affecting you with your girlfriend, your family and your friends that the best approach could be group therapy. I would encourage your to find a local therapist (the find help tab at the top will do it) and look for someone who spcializes in groups. You may also want to look for someone in the American Group Psychotherapy Association.
Group therapy can help you with the anxiety you feel from wanting separation, the desire to improve your relationships, and the desire to balance between your needs and the needs of others. I think it will give you the most direct help in getting what you want.