I am sorry to hear that you child has a attachment disorder and it sounds like it could be RAD( Reactive Attachment Disorder) which means things will get terribly worse once you marry. I know because my child has RAD and all he does is cause problems with in my marriage. The symptoms for RAD are very severe and you should research the web. Here is one that explains the behavior symptoms clearly.
RadKid.Org: Sighs and Symptoms for more information. Keep being strong and fight for all those that you love.